Dauntless 16 Engine Mounting Height, Propeller Pitch

Optimizing the performance of Boston Whaler boats
keithp66
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Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby keithp66 » Mon Sep 21, 2020 10:23 pm

I have a 2001 Dauntless 16 with a 2000 Mercury 90 two-stroke-power-cycle engine. The carburetors were recently tuned. The spark plugs were recently replaced. The engine mounting height is one-hole-up.

The propeller is 12.25-inch diameter and 17-pitch. The propeller is at least five years old and of unknown brand.

With only me aboard and with a full fuel tank, the 2001 DAUNTLESS 16 has good [acceleration from a standing start onto hydroplane], and the maximum boat speed is in a range of 33 to 35-MPH at an engine speed of 5,500-RPM. For the Mercury 90 engine to accelerate to 5,500-RPM the engine trim must be moved out quite a bit. The Mercury 90-HP two-stroke-power-cycle engine does not like full throttle without being trimmed out. It will growl.

With two adults [the boat maximum speed is reduced to] 31 to 33-MPH [and the engine will only accelerate to] 5,200-RPM. [The time to reach plane] is still decent.

Is the the engine mounting height too low?

If the engine mounting height were raised one-hole what difference in performance would occur?

If the engine mounting height were raised two-holes what difference in performance would occur?

If the engine mounting height were raised one-hole would [the propeller ventilate] in rough conditions?

If the engine mounting height were raised two-holes would [the propeller ventilate] in rough conditions?

A mechanic suggested we leave the engine mounting height as is, and he recommended reducing the propeller pitch to 15-pitch because the engine is 20-years-old and is tired. I do not want to give up more top speed.

If a new propeller of 17-pitch were tried, would the performance be difference from the existing propeller?

I am not ready to re-power. I plan to continue to use this engine.

Advice on set up will be welcome.

ASIDE: I know this subject has been covered in other topics, but to weed through all the threads to get clear answer is hard.

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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby jimh » Tue Sep 22, 2020 7:48 am

To predict--that is, to give "a clear answer"---what change might occur in the future with a change in engine mounting height or with a change in propeller pitch is difficult to accomplish with any certainty. Generally about all one can say is raised mounting height tends to reduce drag from the gear case, which often results in an increase in boat speed. It also tends to result in a reduction in cooling water pressure. Experimenting with higher engine mounting heights should be done with the aid of a water pressure gauge and an engine temperature gauge in order to be certain that engine cooling is not being compromised by engine mounting height being too high. As for a change in propeller, an increase in propeller pitch tends to increase the load of the propeller on the engine; that tends to reduce engine speed at full-throttle. A decrease in propeller pitch tends to reduce engine load; that tends to increase engine speed at full-throttle.

Regarding the propeller being used in the performance reported above:

How many blades does the current propeller have?

What material is the current propeller made from?

Regarding propeller ventilation with higher engine mounting:

The higher the engine mounting, the closer to the surface of the water the propeller blades will be operating, which increases the tendency for the propeller to ventilate. Whether or not the old unknown propeller of unknown number of blades and unknown material will have a tendency to ventilate if the engine mounting height is raised 0.75-inches (on-hole-up) is impossible to know with certainty. Much depends of the propeller design and how far the blade tips actually are from the anti-ventilation plate. Note that propellers with raked blades tend to be smaller diameter and therefore will operate farther away from the anti-ventilation plate than a propeller without as much blade rake. This often results in reporting of raked propellers being able to tolerate higher engine mounting heights, which is attributable to the blades actually being more deeply immersed compared to propellers without as much blade rake.

Regarding the performance that would occur if a new propeller on unknown number of blades and unknown material but also 17-pitch were used: predicting the performance change is difficult because little is known about the existing propeller and nothing is known about the proposed new propeller except its marked pitch would be the same as the marked pitch of the existing propeller.

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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby jimh » Tue Sep 22, 2020 8:03 am

Regarding the sound of the engine at various engine speeds: the engine sound often can be used as an indicator of engine loading. Engine sound varies with engine speed. Some engines exhibit a tendency to produce a more resonant engine sound at particular engine speeds, often associated with an increase in engine speed. The exhaust note of an engine laboring under a load that is limiting the ability of the engine to accelerate may have a deeper pitch than will occur with higher engine speeds.

It is particularly natural for the engine sound or note to vary with a two-stroke-power-cycle engine because the exhaust valve timing is generally fixed. At certain engine speeds the physical dimensions and shape of the engine exhaust path creates a reflected wave condition with improves exhaust flow. This tends to permit the engine speed to increase, and allows the engine to produce more power. In many cases the exhaust path length and shape can be tuned to enhance this effect with the intent of producing more engine power output and greater engine speeds. In the particular instance of a Mercury 90 engine, I don't have any basis to predict the engine speed at which a beneficial resonance in the exhaust path might occur and result in a boost in engine power, but typically such an event would occur in the upper one-third of the engine operating speed range.

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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby jimh » Tue Sep 22, 2020 9:31 am

From your narrative, the DAUNTLESS 16 has good acceleration onto plane, reaches a top speed of 35-MPH with a 90-HP engine, and the engine accelerates to 5,500-RPM. I am not certain what you believe can be improved in the boat's performance by changing the propeller. Please give a clear statement of the performance goal you want to achieve.

No information was furnished about the manufacturer's recommended full-throttle engine speed operating range, but I would anticipate that for a Mercury three-cylinder two-stroke-power-cycle engine, an engine speed of 5,500-RPM is in the upper portion of the manufacturer's recommended full-throttle engine speed operating range. This can be interpreted as the engine is producing its rated horsepower output at full throttle. Regarding the engine being described as "tired" by your mechanic: did the mechanic take any cylinder peak pressure measurements?

Do you know the engine hours and history of the engine?

Have you noted any decline in the engine speed at full-throttle over your experience with this engine?

You mention being aware of prior discussions about the performance of a DAUNTLESS 16. Have you reviewed those prior discussions and reports of performance for the DAUNTLESS 16 with an eye to noting the actual boat speeds that have been obtained with engines of 90-HP?

Can you cite other reports for the DAUNTLESS 16 with 90-HP engines that produced significantly higher top speeds than you are presently getting with your engine, engine mounting height, and propeller?

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Phil T
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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby Phil T » Tue Sep 22, 2020 2:22 pm

Based on the limited information (missing make/model of prop, engine height) I would proffer your current performance is at the low end of the expectation for that model boat and engine. There should be a part # stamped on the outside or inside of the hub.

Seeing that individual dealers installed engines in 2001, there is no way to determine which prop was selected.

Running solo with a full fuel load, in calm sea state, trimmed out, I would expect the Dauntless 16 with a Mercury 90hp 2 stroke to reach 40mph measured by GPS.I would suggest you raise the engine so that the top engine bolt is in the 3rd hole from the top and a stainless prop is selected.

Given that every make/model of prop is unique, whaler owners have tested many prop models with the classic Mercury 90hp engine. Based on your model I would suggest you consider:

13-1/4" x 19” Laser II / Lightspeed
13-1/4" x 17” Turbo 1 / Stiletto Advantage
*prop size only applies to specific model listed. Engine mounted "2 holes up"
1992 Outrage 17
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biggiefl
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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby biggiefl » Tue Sep 22, 2020 3:00 pm

I always start with engine mounted all the way up and go from there. Easy to lower an outboard on the trailer using the tongue jack. Most of the time it stays on the highest hole. The higher the engine is to the surface, the less trim needed as the prop is that much closer. Usually a highe mounted engine makes it porpoise less. A good SS prop is needed for higher elevations. An aluminum is not designed for that. The Turbo 1 props are are economical props compared to OEM so I would buy new. The Laser II is a Mercury prop and probably a couple hundred more than a turbo but should be able to find used for about $150-200.

Don't forget to caulk the engine bolts when reinstalling.
On my 24th Whaler. Currently in the stable: 86 18' Outrage, 81 13' Sport(original owner), 87 11' Sport, 69 Squall(for sale cheap).

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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby biggiefl » Tue Sep 22, 2020 3:14 pm

Here is a good link for answers. Looks like all the way up mounting on a 160 is not going to be good.

http://continuouswave.com/ubb/Forum4/HTML/003623.html
On my 24th Whaler. Currently in the stable: 86 18' Outrage, 81 13' Sport(original owner), 87 11' Sport, 69 Squall(for sale cheap).

keithp66
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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby keithp66 » Tue Sep 22, 2020 6:46 pm

The prop is a 3 blade aluminum. I will try and figure out the make model.

The engine is raised one hole from the top. I think this is the two hole. I'm not sure of the actual height.

WOT range per manufacturer is 5000 to 5500.

I plan on checking the compression when we pull the boat for the season next month. I don't think it has a ton of hours. We know the original but not real well. For many years if was a 2nd boat and sat on a morning.

Not looking to go faster necessary. Was wondering why the engine seems adverse to WOT unless trimmed way out. Made me think the engine was too low but just guessing on this. It's fine at 3/4 throttle, 4200 rpm with the motor trimmed closer.

Lupi
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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby Lupi » Wed Sep 23, 2020 5:29 am

I own this boat with same [Mercury 90-HP three-cylinder two-stroke-power-cycle outboard] engine. The "stock setup" (as given to me by Boston Whaler's Chuck Bennett):
  • engine mounted one hole up
  • with aluminium Black Max 13 x 19
  • top speed 39.1-MPH at 5,500-RPM engine speed with two people
I [cound] not develop more about overall performances with this setup. When I bought my used Dauntless 16, it was equiped with an aluminium 16-pitch propeller of an unknown brand and top speed was around 30-MPH with bad overall performances.

My setup after discussions with several people here on this forum:
  • engine mounted three holes up
  • Stiletto Advantage 13.25 x 17 stainless steel propeller.
  • Top speed 39.3-MPH at 5,500-RPM with great acceleration with four people on board, nearly empty tank
I am happy with this performance.

Stiletto propellers are discontinued but Turbo propellers are identical. I remember they [TURBO propellers] are made with even pitch numbers when Stiletto propellers had odd pitch numbers.

I confirm the [recommended manufacturer full-throttle engine speed range] is 5,000 to 5,500 [RPM]for [a Mercury 90-HP three-cylinder two-stroke-power-cycle outboard].

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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby keithp66 » Thu Sep 24, 2020 7:53 pm

So it appears the only difference is you have you engine down one hole and probably a better propeller. Seems like [making those changes to my boat will be] worth a try.

[Does the engine have any problems in] engine cooling?

[Does the propeller have any problems] maintaining a good grip in heavier seas?

We often end up in 2- to 3-foot seas coming back in the afternoon.

Please give me any other specifics on the propeller you are using.

I would like to look for [that propeller you are using for sale] on line.

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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby Lupi » Fri Sep 25, 2020 3:32 am

[The engine does not have problems with] with cooling.

[The Stiletto Advantage 13.25 x 17 stainless steel propeller] grip is good, as well.

This propeller is really designed for surface piercing. You can check for Turbo 1 13-1/4" x 17", as per Phil recommendation.

I just saw that finally Turbo was also doing propellers with odd pitch numbers.

[Mounting the engine at] three-holes-up is fine.

This [Stiletto Advantage 13.25 x 17 stainless steel] 17-pitch propeller has blade cup, so it turns as a 19-pitch at high speed. There are also holes ventilation for better [acceleration from a standing start]. I've never had trouble with [acceleration from a standing start] even with seven people on board.

I live in Brittany in France. The Atlantic Ocean sometimes has offshore conditions. I would say that the propeller is doing well in those rough conditions, and I tend to say that the size of the boat is more a concern.

As Phil mentioned, the Mercury Laser II propeller i 13-1/4" x 19 is also a good choice.

--Luc

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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby keithp66 » Sun Sep 27, 2020 10:49 pm

Thanks for the responses, everyone. The information shared will be very helpful with set-up for next season.

ASIDE: Luc—I went to Brittany about 25 years ago. I remember it being a beautiful place.

Lupi
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Re: Brittany Beauty

Postby Lupi » Mon Sep 28, 2020 11:00 am

Indeed beautiful place. I spend here summer vacations since I was born. We love that place (Crozon peninsula). Here attached a picture taken this summer. The two boats here are my Dauntless 16 with my sister's whaler (1962 Vintage Sakonnet 16, one of the first Whaler imported in France).

Picture Brittany.JPG
Picture Brittany.JPG (125.5 KiB) Viewed 18861 times


Keep us informed about setup and performances next season
Best
Luc

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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby seamuspg » Wed Sep 30, 2020 8:06 am

I have this same exact boat and same concerns and curiosities about my 2001 Dauntless 16 with a Mercury 115-HP (2+2). I bought [the boat in the summer of 2020] and figured I’d use it for one season before tackling any changes. Top boat speed is 31 to 33-MPH. I have a 17-pitch 13.25-inch aluminum four-blade propeller. My engine is mounted one-hole up.

Is one-hole-up mounting how this a DAUNTLESS 16 came [from the dealer]?

In 2021 I may raise the engine mounting height to be two-holes up or to be three-holes up.

In 2021 I may look into changing to a new steel propeller with four blades.


ASIDE TO THE OP:

Q1: How have you enjoyed your boat?

Q2: Are you finding that at a boat speed of 8 to 17-MPH to stay on plane can be tricky or impossible?

MY DAUNTLESS 16 is stern heavy.

The engine being a 2+2 doesn’t help my cause. The final two cylinders kick in at 7-MPH requiring an all-or-nothing move to deal with the added thrust.

Otherwise you are now bow high at 8-MPH with an engine that wants to push through. At that point I need to open it up. I find myself pushing hard on the throttle and just as [the DAUNTLESS 16 boat] starts to fall into plane, I am slowly backing off the engine throttle. It’s not ideal, but I’m learning. [This behavior of the Mercury 115-HP 2+2 engine on the DAUNTLESS 16 hull] also makes slowing down difficult. The boat will swamp the [stern] unless I fully trim down before deceleration. And, as soon as I am back into two-cylinders, I have to push the throttle ever so slightly to avoid the oncoming rush of water.

Someone, please give advice for dealing with this behavior.

All this being said, I have loved the [the DAUNTLESS 16]. I’m not a materialistic guy, but no other single purchase has added more to my quality of life than this little boat. In typical cliched fashion, I only wish I’d done it sooner.

Cheers

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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby GoldenDaze » Wed Sep 30, 2020 10:10 am

Keith, I agree with Phil that your performance seems a little on the low side of the normal range for 90 HP. Lupi's numbers from BW match what's been historically reported by 160 Dauntless owners with the 90 HP 2-stroke engine, a top speed of about 39 MPH. The fact that you're reaching 5500 RPM at only 33-35 MPH suggests to me that you would benefit from a prop with a bit more pitch. On the other hand, if you are loading up with only 2 adults and your maximum engine speed is dropping to 5200 RPM suggests that the motor doesn't have a lot more to give. You would almost certainly benefit from switching to a stainless steel prop, but it's hard to say whether it would be worth it. And how often do you run over 30 MPH anyway? I spend almost all my cruising time at 22-25 MPH. One additional thought -- consider that you have a huge 45 gallon fuel tank on a small boat, that's nearly 300 pounds of fuel. Maybe you should just fill it halfway unless you're heading offshore.

Seamus, you are experiencing the fact of life of a planing hull. You can happily run up to about 6 MPH, and faster than that you're just making noise and waves until you get up on plane. With trim tabs I can stay on plane as low as 16-17 MPH, but without them it would be hard to run lower than 20 MPH. When you decelerate, don't pull the throttle back to idle. Instead, just back off a bit, perhaps half throttle, and let the boat fall off plane more gradually. When the stern wave catches up to the stern and the boat levels out some, then throttle back to idle.

-Bob
2003 160 Dauntless Golden Daze

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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby biggiefl » Wed Sep 30, 2020 10:37 am

Just about every boat with a low transom will take on water if you just pull the throttle back.

How far trimmed-in are you when you try and get on plane?

The engine trim should be all the way in and once you get on plane you start trimming out and pulling back on the throttle in a single motion.
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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby keithp66 » Wed Sep 30, 2020 8:59 pm

Thanks Bob

Definitely getting a stainless steel propeller in 2021. The one that's on there right now has seen better days. I can see slight warping in one if not all the blades. I have an old aluminum 19p I could try out to see how it preforms before I buy a new SS one. I was reading that a vented prop might work well with the two stroke engine. I think the two props Phil recommended are both vented. That would be one decision. Also reading that a lot of the new SS props have a progressive pitch. Seems like this could be the best of both worlds. Does anyone have experience with this kind of prop?

It would be fun to go a little faster but it is more important for me to be able to keep the boat on plane at 4000 rpm with it loaded up with people and stuff in two-foot seas—which we often experience in Vineyard Sound.

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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby keithp66 » Sun Oct 18, 2020 7:39 pm

The boat was pulled out of the water for the end of season in October, 2020.

I found out the current prop is a Quicksilver Black Dimond aluminum 13.25 x 17P (QA3036X).

Next Spring I may want to get a stainless steel propeller. I think the Turbo 1 13.25 x 17P might be the best option.

Should the pitch be increased to 19 since the Turbo 1 is vented and cupped?

I have concern that [a new propeller] won't make an improvement to justify its cost.

A compression test will done on October 24 or 25, 2020. I don't think this will show any defect. I want to be sure.

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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby jimh » Mon Oct 19, 2020 8:42 am

Thanks for the update that your resolve to get a new propeller has changed from “definitely” to less sure.

Thanks for the notice of plans for the future diagnostic tests on the engine.

Re what pitch stainless steel propeller ought to be purchased: predicting propeller outcomes is not an exact science when changing many elements at once: aluminum to steel, one brand to another, one style to another.

The best method is to arrange a trial, and test a new propeller on the basis of being able to return it and exchange for a different pitch at no additional cost except the price difference.

With the boating season ended for you, you’ll have six months to ponder the value created by a new propeller compared to its costs. You seem to have changed your mind from the project being “worth a try” to having doubt about the value.

All our boating is really recreational so all aspects are costs. With gasoline now selling at $1.85-per-gallon, the notion that a new $400 propeller could return a tangible benefit in reduced cost of fuel consumed is very unlikely.

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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby Lupi » Tue Oct 20, 2020 7:55 am

For sure you should get better all around performance by switching to a steel propeller.

Regarding the TURBO propeller [that may in the future be purchased]: it has exactly same design and specifications as the Stiletto [propeller] I have on my boat. [You should] stick to the 13.25 x 17-pitch. A 19-pitch would certainly be too much [load, and the engine] would not exceed 5000-RPM—even with the [propeller hub] vents [set to] open. The engine [under discussion] allows 5500-RPM.

Note that the vents are mainly helpful for [acceleration from a standing start]. At [higher boat] speeds [the propeller vents] do not operate.

As you mentioned, the Turbo [propeller blades have] cupping. [The blade cup makes] a 17 pitch work as a 19-pitch at [higher boat speeds].

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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby Phil T » Tue Oct 20, 2020 8:35 am

Keith - Review the 5th post with prop model and size recommendations.
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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby jimh » Tue Oct 20, 2020 9:25 am

I doubt hub vents will be useful on the boat and engine under discussion. Hub vents might be useful on a 75-MPH boat turning a 25-inch pitch propeller.

Having driven a boat with vented propellers I found the engine throttle response to be awkward, and the intentional loss of propeller grip under acceleration to be bothersome.

If anyone has actually tried using propeller vents on a 17-pitch propeller on 16-foot boat, let’s hear from them—if such a person exists.

Most modern propellers have blade cup. The designated pitch should not be reinterpreted to be 2-inches greater because the propeller has blade cupping. Modern propellers employ progressive pitch changes across the blade face. The designated pitch is presumed to be an effective pitch based on the total blade design. Even if an existing propeller with no blade cupping were reworked to have blade cupping, the effect would be very unlikely to produce a propeller pitch of 2-inches greater than original designated pitch.

None of this is particularly pertinent to the discussion until the OP decides he will buy a new propeller. If the OP decides to buy a new propeller, we won’t find out what change occurred in the boat performance until he conducts careful testing and presents the data. With the boat in storage that will not be happening for many months. Since data from the original propeller is a bit sketchy, to discover exactly what change in performance was realized will be difficult.

It is hardly a secret that fitting a steel propeller of modern design with thinner blades, stronger blades with less flex, with blades with progressive pitch, and with blade cup could improve boat performance compared to a five-year-old three-blade aluminum propeller that is described as having “a slight warping in one if not all three blades” and as having “seen better days.”

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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby biggiefl » Tue Oct 20, 2020 10:58 am

I do not run vented props on any of my boats, even the ones that ran 70mph. With a boat like the one in question I highly doubt I would run an open vent as like Jim mentioned, they have the tendency to slip and make certain speeds awkward. If you buy one and don't like the vent you can just fill it with epoxy.
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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby keithp66 » Tue Oct 20, 2020 11:22 pm

Thanks everyone for your feedback I find this forum very helpful. Appears unanimous that changing to a stainless steel prop will make a noticeable difference. Also, seems like I should stick with the 13.25 x 17P versus going up to a 19P. From what read, Luc, you are using a vented prop. You have the same boat and motor as us. You seems very happy with your boats performance and recommended the Turbo 1 as it has he same design as the Stiletto, which is discontinued. The Turbo 1 is also vented. Phil, you recommended this prop along with the Laser II (quite a bit more expensive). However, others are recommending against a vented prop. Jim and Big, you seem to have had a different experience that was less positive. I read that the vented props are more effective on two stoke motors. Like you say Jim, I guess I'll have to experiment to find the right set up. This has helped me narrow down my choices though. Too bad I have to wait until May to try whatever I get out...

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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby Lupi » Wed Oct 21, 2020 2:44 am

Yes, happy with my setup:

Stiletto [13.25 x 17-pitch] stainless steel, same as the TURBO. My propEllen is vented. I did not plug the vents. Maybe I should,but I am happy like this. Note that the vents have small diameter

Engine mounted three-holes-up, as per diagram below

0
0
0
0<---- bolts here
0

As per Phil, recommendation, the [LASER II] 13.25 x 19-pitch is also a good choice that had been recommend to me in the past. [The] propeller [has vent holes] with the possibility to adjust the diameter of the holes or to plug them.

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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby GoldenDaze » Wed Oct 21, 2020 9:45 am

If anyone has actually tried using propeller vents on a 17-pitch propeller on 16-foot boat, let’s hear from them—if such a person exists.


Well, as it turns out, that would be me. My 160 Dauntless with a 2003 Mercury 115 HP 4-stroke (with the Yamaha powerhead that I refer to as "The Torqueless Wonder") has been running a 17" pitch Mercury Trophy Plus for years. The Trophy Plus is a vented prop, and I have it set up with medium vent plugs. I also tried it with solid plugs (no venting), but the engine was less able to get spun up into its high-torque RPM range to get the boat planed off. It wasn't awful, but it wasn't as prompt as with the medium vents. I also tried it with the vent plugs out entirely (maximum venting), but that allowed too much ventilation of the prop, and the RPM spun way up without enough thrust. Once the boat speed gets above 22 MPH or so, the vents don't seem to have any further effect.

Mercury also makes small and large vent hole plugs, but after experimenting with the three settings above I was satisfied with what I had and moved on to other things.

-Bob
2003 160 Dauntless Golden Daze

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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby keithp66 » Fri Oct 23, 2020 7:21 pm

I [measured the cylinder pressure on October 23, 2020] with the engine hot, throttle at half, and safety lanyard switch off. Top [and middle] cylinders [measured] 120-PSI; the bottom [cylinder measured] 115-PSI. [These measured values of cylinder pressure to me] seem pretty good for a 20-year-old engine.

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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby jimh » Sat Oct 24, 2020 11:48 am

KEITHP66--how does the outcome of your measurement of cylinder pressure affect your decision to buy or not buy a new propeller next Spring?

keithp66
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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby keithp66 » Sat Oct 24, 2020 7:23 pm

I guess [the outcome of the cylinder pressure test] tells [me] that the engine has some life left and a new stainless steel propeller would be a good investment.

Since I stated that I was going to do the test, I thought I would share the results.

jimh
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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby jimh » Sun Oct 25, 2020 10:08 am

KEITH--To share the results of the test for cylinder pressure is perfectly good information, and I don't think there is any basis to object to that information being "shared", nor was there any notion on my part that you should not have shared that information.

It is not the information that is particularly of interest; I am more interested in your plans for the future in regard to buying a new propeller and how they are going to be affected. Throughout the thread you have expressed varying amounts of interest in buying a new propeller, so I was interested to know if the test results would increase or decrease your interest in buying a new propeller. A new propeller might be, as you say, "a good investment", but the question is: will you buy one based on the outcome of the pressure test?

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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby jimh » Sun Oct 25, 2020 10:13 am

GoldenDaze wrote:My 160 Dauntless with a 2003 Mercury 115 HP 4-stroke (with the Yamaha powerhead that I refer to as "The Torqueless Wonder") has been running a 17" pitch Mercury Trophy Plus for years. The Trophy Plus is a vented prop, and I have it set up with medium vent plugs.


BOB--many thanks for contributing this interesting information on using propeller hub vents on your 115-HP engine on the 160 DAUNTLESS with the TROPHYplus propeller. The medium vent size sounds like it has enhanced the performance, without too much (of what I call the) "rubber-band-effect" (where it seems like the engine is connected to the propeller by some sort of flexible coupling that must be wound up to get to a more direct transfer of rotation).

keithp66
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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby keithp66 » Sun Oct 25, 2020 8:48 pm

Nothing is guaranteed but I'm 99% sure I will get a new stainless steel propeller. The opinions on this thread that it will improve performance are very convincing.

As mentioned, based on recommendations, I really like the Turbo 1 in the same diameter and pitch (13.25 x 17) as I have now.

More recently, I learned about and am also interested in the Turning Point Express Mach 3 (13.25 x 17). It's appears to be very similar to the Turbo 1 (vented, cupped, progressive pitch) but is a little bit less expensive. I don't recall [the Turning Point Express Mach 3 propeller] ever being mentioned on this forum in the threads I've read though.

[I am interested in hearing form Boston Whaler boat owners who have] experience with [a Turning Point Express Mac 3 13.25 x 17 propeller.

To save a few dollars would be nice.

biggiefl
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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby biggiefl » Mon Oct 26, 2020 11:37 am

A Turbo propeller is an inexpensive propeller compared to OEM propellers. I have never heard of Turning Point propellers.

If the cost of a propeller is your biggest concern, start looking on eBay for a used OEM or Turbo propeller.
On my 24th Whaler. Currently in the stable: 86 18' Outrage, 81 13' Sport(original owner), 87 11' Sport, 69 Squall(for sale cheap).

keithp66
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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby keithp66 » Wed Nov 11, 2020 4:54 pm

Luc--does [your DAUNTLESS 16 boat] have a notch in the [hull at the transom]?

The 2001 [DAUNTLESS 16] has a notch [in the hull at the transom].

[With an engine mounting height of two-holes-up on a 2001 DAUNTLESS 16] the [engine's anti-ventilation] plate is above the bottom of the keel, but below the bottom of the notch.

Is [the location of the anti-ventilation plate on the engine on your boat] the same [as I have described above]?

Lupi
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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby Lupi » Thu Nov 12, 2020 2:37 am

Yes, [my DAUNTLESS 16 boat has] the notch.

I guess [Boston Whaler stopped manufacturing the DAUNTLESS 16 boat with a notich] when they they switched to the 160 DAUNTLESS model.

[The 160 DAUNTLESS] is [the] same boat [as the DAUNTLESS 16] but with some slight improvements

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Re: Dauntless 16 Engine Mounting Height, Propeller Pitch

Postby jimh » Wed Nov 18, 2020 11:12 am

Thread now closed. Please start a new thread to present the outcome of the re-fitting of the DAUNTLESS 16 boat that has been the topic of this discussion with a new propeller after you select a new propeller and conduct some performance test in 2021.

When you begin the new topic on the new propeller, please include the rather brief performance data you presented in this thread so readers can compare the results with the new propeller to the performance you reported with the old propeller in this thread without having to sift through this entire thread to find that information. As you noted earlier, "to weed through all the threads to get [a] clear answer is hard." Save others from that drudgery.

As mentioned before, I am confident that the performance with a new stainless steel propeller with thinner blades, with stronger blades with less flexing, with progressive pitch, and with blade cup, will exceed the performance you were getting with a five-year-old three-blade aluminum propeller that is described as having “a slight warping in one if not all three blades” and as having “seen better days.”

I am looking forward to hearing the outcome in 2021.