160 Dauntless 115-HP Propeller Recommendation

Optimizing the performance of Boston Whaler boats
seamuspg
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160 Dauntless 115-HP Propeller Recommendation

Postby seamuspg » Thu Aug 06, 2020 12:44 pm

[Moderator's note: this thread had been moved to the PERFORMANCE forum because the thread solicits advice on improving the performance of a boat. The PERFORMANCE forum is specifically focused on discussions of performance enhancement. The use of a different propeller is not considered a repair or a modification. Propellers are routinely changed to suit different operating conditions.]

I recently damaged my boat propeller exploring some shallow waters. I have a [2002--always use four-digits for years] Mercury 115-HP ELPTO 115 two-stroke engine

What are the best options for a propeller for a heavy [160 DAUNTLESS] boat.

I want to stay with an aluminum propeller as [propeller damage due to grounding in shallow water] could happen again.

The boatyard mechanic advised against switching propellers since the engine has been adjusted to that certain pitch.

[Is it]True [that an outboard engine is adjusted to suit a particular propeller]?

Is getting the pitch and width of my current propeller [information that is more valuable than any other]?

Thanks,
Seamus

jimh
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Re: 160 Dauntless 115-HP Propeller Recommendation

Postby jimh » Thu Aug 06, 2020 1:16 pm

seamuspg wrote:I recently damaged my boat propeller exploring some shallow waters...The boatyard mechanic advised against switching propellers since the engine has been adjusted to that certain pitch.

[Is it]True [that an outboard engine is adjusted to suit a particular propeller]?


The mechanic who told you the outboard engine is adjusted to fit a particular propeller probably knows better. He was probably trying to explain to you, a novice boater, in a simple way the relationship between boat, engine, and propeller. No one could keep a job as a boat mechanic if he really thought you adjust the engine to fit a propeller.

The actual situation is just the opposite of what you attribute to him saying. There is no means to adjust the engine, so the propeller is selected to fit a particular boat-engine combination. In essence you adjust the propeller (by picking the right one) to fit the engine and boat.

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Phil T
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Re: 160 Dauntless 115-HP Propeller Recommendation

Postby Phil T » Thu Aug 06, 2020 2:09 pm

The adage "aluminum props are better" is outdated and now false due to the introduction of shock absorbing hubs. Stainless props deliver better performance, efficiency and are less prone to damage.

Dealers/yard guys say aluminum because they are cheap, cheaper for them to stock and will lead to you coming back again and replacing it when it gets damaged. I have never had to replace a stainless prop due to damage (and I have hit some hum dingers)

You should find a different boatyard mechanic, he is not working for your interests.

The 2002 Mercury 115hp has a gear ratio of 2.07 and a WOT range of 4750-5250. The target speed is 40mph based on other owners.

The prop calculator returns a pitch of 17".

Good candidates include:

Trophy Plus - https://www.mercurymarine.com/en/us/propellers/elite-series/trophy-plus/
Vengence - https://www.mercurymarine.com/en/us/propellers/sport-series/vengeance/

Engine should be mounted with the top bolts in the 3rd hole down from the top, also called "2 (empty) holes up"
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biggiefl
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Re: 160 Dauntless 115-HP Propeller Recommendation

Postby biggiefl » Thu Aug 06, 2020 2:13 pm

Don't buy another aluminum prop and keep yours for a spare.
On my 24th Whaler. Currently in the stable: 86 18' Outrage, 81 13' Sport(original owner), 87 11' Sport, 69 Squall(for sale cheap).

fno
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Re: 160 Dauntless 115-HP Propeller Recommendation

Postby fno » Fri Aug 07, 2020 9:50 pm

Seamus, if you want to try a SS Vengeance prop. I have one in 16 pitch with a small ding on one blade. Not enough to affect performance in the short run but could and should be fixed. I will send it to you to try it and if you want to keep it, send me $100. You will have more than enough left over for the repair compared to buying a new propeller.

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GoldenDaze
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Re: 160 Dauntless 115-HP Propeller Recommendation

Postby GoldenDaze » Sat Aug 08, 2020 7:15 am

I have the 115 4-stroke rather than the 2-stroke but I'd expect the four-blade 17-pitch Trophy Plus to be a good choice for you, too. The extra blade area is good for pushing the boat up on plane. I felt that my original Vengeance 16-pitch was more of a top-speed propeller, and that wasn't as important to me.
2003 160 Dauntless Golden Daze

seamuspg
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Re: 160 Dauntless 115-HP Propeller Recommendation

Postby seamuspg » Wed Aug 12, 2020 8:26 am

The damaged propeller was a Quiksilver 13 x19 three-blade.


I had access to a Turning Point three-blade 17-pitch. I figured I'd give it a go as it seemed to be in the ballpark of what most were recommending for my boat and engine. My engine is rated for 5280-RPM on sticker.

Explain to me what that means when it comes picking in the right propeller?

I did notice [an increase] in top speed to 35-MPH from 32-MPH with the new propeller. I'm not sure [the engine] was able to get [the boat] to plane any quicker. I plan on taking her out again to see what sort of differences I can feel.


How does one tell what "notch" they have their engine mounted to on the transom?

Is [the "notch"] the five holes on the engine mount?

I look but I don't see any other holes for [the engine] to be attached.

I must be missing something.

Thanks

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Phil T
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Re: 160 Dauntless 115-HP Propeller Recommendation

Postby Phil T » Wed Aug 12, 2020 12:08 pm

Please clarify -

My engine is rated for 5280 rpms. (on sticker)


What "Sticker" and where is it? Can you share a photo?

Which of the following is what you see:

Top of engine bracket holes
0 - "all the way down
0 - bolt here is "1 holes up"
0 - bolt here is "2 holes up"
0 - bolt here is "3 holes up"
0 - bolt here is "4 holes up"

I think your speed is too low. You may need to raise the engine and drop down 2" of pitch in the same make/model of prop.

Aside - Bob, Do you hit 40 with your setup?
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jimh
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Re: 160 Dauntless 115-HP Propeller Recommendation

Postby jimh » Wed Aug 12, 2020 12:48 pm

To learn how to describe engine mounting height, please read the article that is located at the top of the index listing of articles in this forum with the TOPIC "Engine Mounting Height." Rather than repeat the article describing engine mounting height every time someone asks about it, I just ask new participants to please just read the article that explains it in detail.

If you are having difficulty navigating the forum, the ENGINE MOUNTING HEIGHT article is located at

viewtopic.php?f=7&t=739

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Re: 160 Dauntless 115-HP Propeller Recommendation

Postby jimh » Wed Aug 12, 2020 12:53 pm

seamuspg wrote:How does one tell what "notch" they have their engine mounted to on the transom?


The term "notch" is not used to describe engine mounting height. However, many Boston Whaler boat transoms have a cut away or notched-down center portion for the engine to be mounted. The purpose of the notch is to create the appropriate transom height. Without the notch or cut away center portion of the transom, the shaft length of the outboard engine would need to be longer. The normal shaft length of an outboard engine is 20-inches (called "long") or 25-inches (called "extra long' or XL). Only recently have outboard engines with 30-inch-shaft length been available (called "extra-extra-long" or XXL). For some models of Boston Whaler boat made years ago, if there were no notch in the transom the boat could not have properly mounted an outboard engine of that era.

seamuspg wrote:Is [the "notch"] the five holes on the engine mount?


No. Many engines only have a set of four holes on their engine mounts. Recently use of five holes has become more common. The engine mounting plate has been standardized for the arrangement of holes. This is known as the BIA transom hole layout. In this way, it will be possible to mount engines from different brands onto a boat without having to change the hole layout in the transom.

The reason the engine has a set of four or five holes for determine vertical mounting position is to permit the engine mounting height to be adjusted WITHOUT having to drill new holes in the boat transom.

Engine mounting height is described as detailed in the article ENGINE MOUNTING HEIGHT. See my earlier reply for a link to the article. The article is at the top of the index listing in the PERFORMANCE forum of available articles and is easily found.

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GoldenDaze
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Re: 160 Dauntless 115-HP Propeller Recommendation

Postby GoldenDaze » Thu Aug 13, 2020 11:49 am

Phil, I make 42-43 mph with my 115 4-stroke and a 17" Trophy Plus. My old 16" Vengeance gave 44-45 mph.

I agree that Seamus' 35 mph seems too slow for a 115 2-stroke. From memory, that seems slow even for those 160 Dauntless owners with 90 HP engines. While I'm not specifically familiar with the Turning Point 17" prop, and it seems they make both aluminum and stainless steel props, and I don't know which we are talking about here. But a 17" prop seems roughly in the right range for the boat and engine. Seamus, I wonder whether your engine is running on all cylinders.

-Bob
2003 160 Dauntless Golden Daze

gmaster
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Re: 160 Dauntless 115-HP Propeller Recommendation

Postby gmaster » Sun Aug 23, 2020 10:35 pm

Seamus,
I have a 2004 Dauntless 160 with the 115 2 stroke 2+2 engine which I have been the only owner. I had a Michigan Rapture 17 pitch prop which worked great along with a hydrofoil.I could get 45-47 mph with that set up around 5200 at WOT. I recently changed to a new 2019 Mercury 115 CT four stroke.

Bryan

Lupi
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Re: 160 Dauntless 115-HP Propeller Recommendation

Postby Lupi » Mon Aug 24, 2020 10:02 am

Bryan,
You recently changed to a new mer 115 four stroke CT (large gearcase, 2.38). What do you report in term of performance (top speed, holeshot,...) Do you see big improvements compared to the 115 2+2 (except from noise, smoke and vibrations). And what prop do you have with this engine and finally, how is it mounted on the transom (how many holes up).
Thanks a lot
Luc

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Re: 160 Dauntless 115-HP Propeller Recommendation

Postby gmaster » Sat Sep 05, 2020 1:38 pm

Luc,
I am running a Mercury Enertia 21 P prop with the engine mounted one hole up. I have used the new Mercury 115 CT four stroke for 50 hours. I am happy in every way in how it runs compared to my old 2004 115 ELPTO 2+2 2stroke. The power band is much smoother and it has excellent torque and the hole shot is better than the old engine. My current engine at WOT gets 43-45 mph top speed at 5600 rpm. This is just under what the old 2 stroke would do in the 45-47 range. THe old 2 stroke ran great above 3000 rpm and was super fast but under 3000 rpm it was not so great . It didn't start or idle very well. I am very happy with the new Merc CT 115. It is a perfect match for the Dauntless 160.

Bryan