Forum: WHALER
  ContinuousWave
  Whaler
  Moderated Discussion Areas
  ContinuousWave: Whaler Performance
  Would changing out propeller add any significant increase to top end speed?

Post New Topic  Post Reply
search | FAQ | profile | register | author help

Author Topic:   Would changing out propeller add any significant increase to top end speed?
2001 13 Sport Owner posted 02-21-2001 01:15 PM ET (US)   Profile for 2001 13 Sport Owner   Send Email to 2001 13 Sport Owner  
I have a new 13' Sport with the Mercury Big Foot 25 Horsepower 4-Stroke on it. Would changing out my propeller increase my top end speed and improve performance? My current compliant is that when the boat is loaded with fishing equipment and 2 people it is slow to plane and the top end is around 25 mph. Without upgrading to a larger horsepower engine, are there any other modifications I can do that will noticeably increase the performance that make sense economically or should I just go ahead and upgrade to a 40 Horsepower. My goal is to get the boat to plane faster and get a top end speed in the low to mid 30 mph level while loaded with fishing gear and two people. Thanks for your input!
Easy E posted 02-21-2001 09:39 PM ET (US)     Profile for Easy E    
I would put on some doel-fins and i would go with a stainless steel cupped propeller that is one or two pitch up from what your currently using.Being that the engine is a "big foot" it should swing a higher pitch prop with out a problem.Power tilt & trim wouldnt hurt either.With all that you should be able to reach the low 30's or so.Any opinons?Easy E
Dick posted 02-21-2001 10:39 PM ET (US)     Profile for Dick  Send Email to Dick     
A doel-fin and stainless prop probably would help.
Unless you have a tach I would be carefull playing around with props. Not sure what that motor should turn wide open but it should be proped to run there. Increasing prop pitch will lower rpm decreasing pitch will increase rpm.
If you have a tach what are you turning wide open?
What pitch prop are you running?
Dick
2001 13 Sport Owner posted 02-21-2001 11:08 PM ET (US)     Profile for 2001 13 Sport Owner  Send Email to 2001 13 Sport Owner     
Thanks for all the input. I have a couple of other questions and your help would be greatly appreciated. 1. Which doel-fin would you recommend? Stingray or another type? 2. Which propeller would you recommend? The existing propeller came with the engine and I am not sure which one it is, but can call Mercury about it. Thanks!
Dick posted 02-21-2001 11:20 PM ET (US)     Profile for Dick  Send Email to Dick     
Look at the prop where the exhaust comes out, around the rim there will be numbers the last two will be the pitch. Also what about the wide open rpm?
Dick
Easy E posted 02-21-2001 11:56 PM ET (US)     Profile for Easy E    
I would take dick's advise and get a tach(if you dount have one)before you start changin props.According to the merc spec sheet for your engine the standard prop is 10 7/8x11 and max rpm range 5500-6000.
So, if you have a tach or when you get a tach you will no what pitch prop to get.So say you do have the standard prop which is a 11 pitch and your tach reads 5800rpm at WOT, if you get a 12 pitch your rpms would drop to about 5600rpm and you will go faster. Kinda like changing gears in a car.
A 1 pitch change in prop is a 200rpm change in engine speed.
About the hydrofoils, doel-fin and stingray are two diffrent hydrofoils.I would recommend a doel-fin i used it on my 13' and it gave me faster planing and about 2mph gain on top speed because i can get more of the hull out of the water with trim up.Westmarine.com sells it and my local Kmart.
Well i hope this helps...Easy E
Lil Whaler Lover posted 02-22-2001 06:46 AM ET (US)     Profile for Lil Whaler Lover  Send Email to Lil Whaler Lover     
Are we looking for miracles here? Can a prop be found that will improve acceleration significantly and yield a 20% to 40% increase in top speed? All this out of a 25 hp 4-stroke. Gentlemen, the only possible to this dilemma is to get more horsepower onto the boat.
A hydrofoil type of fin whould aid in acceleration by helping the boat get a load "over the hump" to some extent and a lower pitch prop will do the same thing. Keep in mind that the 25 4-stroke on the new 13 Sport is a bigfoot design which means that it already has a larger cavitation plate that the standard engine of that horsepower. That being said the improvement from a Doelfin or stingray may be minimized right up front.
Dick and Easy E are right about needing a tach before you play with changing the pitch of your prop. Lowering the pitch, if you are already operating within the motors recommended rpm range would normally improve acceleration, and lower top speed at the risk of blowing the powerhead by over revving it. Increasing the pitch would normally hurt the acceleration and lower the top speed under load as the engine will be lugging and unable to operate within its normal range.
There are 2 possible helps to this problem. The first is to get any excess weight out of the boat as weight kills performance especially for a small engine like a 25. Secondly get a higher horsepower engine on the boat.
If Land and Sea made a power shift prop for this application you might gain some of your desired performance. They do not make them for low horsepower engines because there is just not enough torque there to make them work. Remember that you just do not have enough horsepower to get large improvements here. Good luck, Dave
tbyrne posted 02-22-2001 10:13 AM ET (US)     Profile for tbyrne    
I agree with LWL - if you need substantially more speed, you will need to move up in HP. I have the same boat (2000 Sport 13 w/ 25 h.p. 4-stroke and tachometer). I fooled around with propellers a bit in the search for more speed, with only modest success.

I run the boat light, usually with just myself and fishing gear. With the factory 11" pitch prop, I would get 6,200 rpm with the motor trimmed out. When I changed to the 12" pitch prop, the rpms dropped to 5,900-6,000 and I got a bit more mid-range and top end speed. So, if you are getting 6,000 with the 11" and a full load, I think you could go to the 12" aluminum wheel.

After I dinged up the 12" prop, I tried a stainless prop from Power Tech. I thought I'd try a 13" to see if I could get the same speed at 5,750 rpms or so. However, when I tried it out, my max rpms dropped to 5,400. I spoke with Midwest Propellers about the drastic drop and they suggested that the reason for it was because the SS prop had greater cupping. Stainless can be cupped more than aluminum because it is not as brittle. If you try to put too much cup into an aluminum prop, it will snap.

As a result, I swapped the 13" stainless for an 11" stainless - I did not have the chance to run it in the fall, but I think it should be about right. I'll report back once the ice is out (hopefully before May!). I don't expect any miracles, but I think it will work out OK.

Good luck and don't expect miracles!

2001 13 Sport Owner posted 02-23-2001 11:27 PM ET (US)     Profile for 2001 13 Sport Owner  Send Email to 2001 13 Sport Owner     
Thanks for all the advice. I will most likely run my boat this season with the 25 Horsepower 4-Stroke and most likely upgrade to a 40 Horsepower engine the following season. I hear the Yamaha 40 HP 4-Stroke only weighs about 181 pounds.
That is very close to the weight on the existing engine. If anyone has any thoughts on the best 40 HP on the market that weighs less than 195 pounds, I would to hear your opinions! Thanks!
Easy E posted 02-25-2001 05:44 AM ET (US)     Profile for Easy E    
The yamaha 40hp 4-stroke weighs about 181ibs in 15in. shaft but the 20in. shaft is more like 195lbs.
2001 13 Sport Owner posted 02-26-2001 11:57 AM ET (US)     Profile for 2001 13 Sport Owner  Send Email to 2001 13 Sport Owner     
I have receently seen other posts on The Classice Whaler forum stating that the 2001 13 Sport is now being offered with the 40HP 4-Stroke engine. In fact two people have said they are purchasing the 13 Sport from Whaler dealers with the 40 HP 4-Stroke. I guess the extra weight is not a problem for the 2001 13 Sport. I just wish they would have offered that package when I bought a couple of months ago. My 25 HP 4-Stroke only has a couple of hours on it. Would it be wise to go ahead and repower now since the engine is almost brand new and has lots of warranty still left on it? Also, would any of you repower with a different brand or stick with Mercury? It would certainly be easy for the dealer to switch with another Mercury since all that would be neccessary is to switch engine while leaving all other controls in place. Any thoughts?
awares posted 02-28-2001 11:01 PM ET (US)     Profile for awares  Send Email to awares     
I will know this weekend if the 40hp 4 stroke
engine is a problem. I just picked mine up today. Something else I found out today from the dealer is that this motor is built by Yamaha. Mercury only supplies the covers.

I will post pictures next week with the boat
setting in the water with and without a load.

You may state your case with Whaler about how
displeased you are and see if they can give you some assistance in exchanging the motor.

Its obvious they saw a problem or they would not have changed the package to include this motor.

I'm sure you are not the only one considering
the change. I would press the issue now and
do not wait until you have several hours on the motor. Get your dealer involved also because he might have a customer interested
in the 25hp if you can get Whaler to help reduce the price.

Nothing travelers faster than a dissatified customer.

2001 13 Sport Owner posted 02-28-2001 11:23 PM ET (US)     Profile for 2001 13 Sport Owner  Send Email to 2001 13 Sport Owner     
Awares, Thanks for the feedback. The dealer I bought from tried to get me to go for the 40 HP 2-Stroke. After going back and forth between the 25 HP 4-Stroke and the 40HP 2-Stroke, I went with the 4 stroke because I wanted an engine that was very dependable and quiet. It would have been the right decision if it had just a bit more horsepower. I must say the dealer was very upfront and did his best to sway me towards the higher horsepower engine. Anyhow, let me know how you like yours and I would love to see some pictures. Other than the lack of horsepower, the boat is awesome. You will be very happy with your new purchase.
jimh posted 03-01-2001 12:11 AM ET (US)     Profile for jimh  Send Email to jimh     
My wife's aunt had an old 13-Whaler (classic) with a 25-HP 2-stroke on it. This was an older motor so the power at the prop was probably only on the order of 20 HP.

We used to run all over in that boat. I know it would plane easily with three aboard.
In fact, I am certain we even did some water skiing with it! All with 25-HP.

I guess people's expectations about how fast a boat should be these days have changed.
And maybe we all weighed a bit less 15 years ago...

Post New Topic  Post Reply
Hop to:


Contact Us | RETURN to ContinuousWave Top Page

Powered by: Ultimate Bulletin Board, Freeware Version 2000
Purchase our Licensed Version- which adds many more features!
© Infopop Corporation (formerly Madrona Park, Inc.), 1998 - 2000.