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  Dauntless 13 with Yamaha 40-HP

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Author Topic:   Dauntless 13 with Yamaha 40-HP
Rocket Jockey posted 04-29-2015 12:18 PM ET (US)   Profile for Rocket Jockey   Send Email to Rocket Jockey  
Hi all. I am a long-time lurker and first-time owner of a Boston Whaler boat. I purchased a 1995 Dauntless 13 with a 1999 [Yamaha] 40 TLRX two-stoke-power-cycle outboard engine. The stock propeller is a 10-3/8 x 13. I want to replace the propeller but need some advice. [The boat] mainly will be used as a water taxi and dinghy and fishing boat, primarily for just my wife and I, with combined weight around 275-lbs. I have moved the motor up on the transom from the bottom hole to the next one higher. The motor also has a hydrofoil model SE 200 Sport. I would like opinions from others on the best overall performing propeller and best budget propeller Thanks in advance for your help--RJ
EJO posted 04-29-2015 12:24 PM ET (US)     Profile for EJO  Send Email to EJO     
RJ--as many will ask, what is your goal with the new propeller? Speed? [Acceleration]? Efficiency? What is the current WOT boatspeed and engine speed? With that information you will get a lot of good advice from the guys here.
jimh posted 04-29-2015 01:55 PM ET (US)     Profile for jimh  Send Email to jimh     
Get some data from your present set up at full throttle:

--engine speed

--gear ratio

--boat speed

--propeller pitch


Enter the data into my PROPELLER CALCULATOR at

http://continuouswave.com/cgi-bin/propcalc.pl

Compute the SLIP for your present configuration. If the SLIP is below 10, the present propeller is probably working well.

Locate the information on the recommended full-throttle engine speed range for your engine. HINT: look in the operator's guide.

Compare the engine speed at full-throttle with your present set-up to the engine speed at full-throttle that is recommended. As a general rule it is preferred that the engine speed at full throttle is in the upper half or upper third of the range suggested by the manufacturer. Some outboard engine manufacturers suggest an optimum full-throttle range with a much narrow range of speeds. If possible, setting up the boat for the engine to reach that speed range is preferred.

Is the present propeller an aluminum propeller?

Rocket Jockey posted 04-29-2015 02:48 PM ET (US)     Profile for Rocket Jockey  Send Email to Rocket Jockey     
Thanks for the quick replies. I will get the info requested, hopefully within the next few days. I have never had this boat in the water and was hoping to get a new prop on before we launch thinking we would probably just leave it at the marina.

I want the boat to get on plane easily and provide all around good performance....hopefully that is not to vague. Again it will be used as a day boat for fun and water taxi for friends. I am guessing 80% of the use will be just my wife and I but obviously when we dingy friends, we will be fully loaded for short trips.

My question was probably a bit premature, just thinking there must be others with the same configuration that had already been through this process. I will use the present prop and get some run data. I am assuming if the prop is in bad shape the data would not be 100% accurate but "prop-ably" better than nothing!!

Thanks,
RJ

Tom W Clark posted 04-30-2015 10:23 AM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
I recommend a 12" x 12" Stiletto Star or Turbo Pontoon 1 be used with this boat/motor combination

Top speed should be near 35 MPH when lightly loaded and this propeller will allow the engine speed to approach its 5500 RPM redline at WOT

jimh posted 04-30-2015 01:10 PM ET (US)     Profile for jimh  Send Email to jimh     
Any propeller that has been damaged and has been bent or twisted or in some way had the shape of its blades changed due to an impact with some object in the water is not going to be a good basis to judge performance.

Tom has a lot of experience in propeller selection, and his advice is usually very likely to produce results that, if not optimum, are very close. In general, propeller optimization usually requires several trial and error evaluations, but sometimes experience can cut that effort down significantly.

Rocket Jockey posted 04-30-2015 02:03 PM ET (US)     Profile for Rocket Jockey  Send Email to Rocket Jockey     
Thanks for the suggestions, much appreciated. Those are on the higher end of what I was hoping to spend. Do you have a budget prop that you can suggest?

Thanks

Tom W Clark posted 05-01-2015 02:30 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
What is your budget limit?
Rocket Jockey posted 05-01-2015 06:39 PM ET (US)     Profile for Rocket Jockey  Send Email to Rocket Jockey     
Tom,
I am undecided on what to do, stainless steel vs. aluminum. for various reasons. So, I am assuming your recommendation for the Stiletto Star was the "best" option, now I wondering what the best "budget" option is. I was thinking around the $100 range.

Thanks for your time and knowledge!!

RJ

jimh posted 05-02-2015 05:33 AM ET (US)     Profile for jimh  Send Email to jimh     
Propellers with costs in the range of $100 are going to be aluminum, if new, or perhaps stainless steel, but only if used.

An aluminum propeller can be fine with a 40-HP engine. Aluminum is not very durable should you have any sort of blade strike.

Tom W Clark posted 05-02-2015 10:48 AM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
$100 will not even buy a replacement of the propeller you have now, though it might be enough to repair your current propeller.

After the boat and motor, the propeller is the single most important piece of hardware. It always amazes me how folks, after spending thousand or tens of thousand of dollars buying a boat will short change the performance of that boat by trying to save a few bucks on the prop.

Rocket Jockey posted 05-13-2015 02:59 PM ET (US)     Profile for Rocket Jockey  Send Email to Rocket Jockey     
I have finally splashed my Dauntless and have spent the last two days playing with it and have some additional info and questions.

The Yamaha 40 has four motor mount locations. I have raised it to the third hole down, from the top. Now the cavitation plate is in the spray when trimmed up at WOT. I am assuming that is the correct position. Yes?

With what would be a typical load, I was able to get 5,400-RPM and 34-MPH (measured with a GPS receiver) with my dinged up stock propeller. I am happy with that but would like to keep it on plane at a lower engine speed and reduce bow rise. Suggestions?

Tom, I appreciate your feedback. The reason I was asking for a "budget" propeller was because I know I can replace my existing with something very similar in a new aluminum prop for around $100. I was looking for brand, diameter, and pitch information. I am not opposed to stepping up to a stainless steel propeller; I just wanted to know my options so I could make an informed decision. Based on what I have now provided, do you think the Stiletto Star 12 x 12 is still my best option?

This boat is an absolute blast. This is a lot of boat in a really small package.

Thanks,
RJ

Tom W Clark posted 05-13-2015 05:11 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
That's pretty good performance with that propeller. Maybe you could just get it repaired.

Yes, I think the 12" x 12" Star would offer a lower minimum planing speed.

Yamaha does not offer any four blades, but Solas makes one for that motor. I do not generally recommend Solas propellers but I have had some good success with their smaller four blade aluminum propellers. You would want a 13-pitch Solas aluminum, three or four blade.

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