Repowering A Dufour (30') with a YSM 8hp Yanmar?

[Du4salr!]

Hello,

New to this forum (see you don't have a Dufour section yet) and am looking forward to learning more and sharing what I know..

I bought my Dufour Arpege' 3 years ago and am almost finished with an extensive refitting of nearly everything.. My last big project (besides repainting the deck and hull) is to repower her.

She originally came with a Renault 16. I have a chance to pick up a Yanmar YSM 8hp that was in a C&C 26. I am curious to know if I can use this smaller engine and get satisfactory results?

It has a 3 bladed prop (don't know the numbers or pitch) so that could be a concern also..

The Arpege' has a displacement of around #7000...

Curious as to what you think about this?

Thanks,
Doug

 

[Steve Dion]

The "general" consensus is that you will require approx. 2 hp/ 1,000 lbs. This would indicate that you would need a min. of 14hp. The estimate does not take into consideration if you are properly propped and how much "stuff" you have added to the boat (like most of us).

 

[larryw]

I'd say 8hp would be barely enough, with no power reserve against wind or waves in bad weather, and a small engine working very hard will use more fuel than a larger engine not working so hard. I'd pass, and try for something larger. You're out there in farm country, see if a farm equipment dealer has some engines. Early Catalina 30s, with a displ of 10,000 lbs, used an 11hp diesel engine Model 5411, based on a Kubota block, which is very common in farm equipment. It was raw-water cooled, so no need for a heat exchanger, and since you are in fresh water, no corrosion issues.

 

[Roger Long]

My 12,500 pound boat goes 5.5 knots with 8 horsepower in calm water. If you will be primarily fair weather sailing and just need to get in and out of the harbor and power cruise in light air, that engine should be fine. If you want to be able to buck head winds and seas, you'll want more.

Very important. If that prop is properly sized for the original 16 hp engine, it will destroy the small engine in short order. However, many boats have props that are too small for the engine installed. I would start there. Many places the sell propellers will do the calculations for you if you can provide them with the info on the boat. You may find that the prop has only been putting about 10 hp into the water anyway.

Most likely, you'll need a new prop to go with that engine.

These folks can help:

http://www.hhprop.com/

 

[Scott B]

I would be leary on Lake Michigan with an undersized engine.

 

[Barnacle Bill]

Welcome Doug. I would say 8 hp might be a little light on Superior when you need to get somewhere in the heavier seas.

 

[Scott B]

Welcome Doug. I would say 8 hp might be a little light on Superior when you need to get somewhere in the heavier seas.

I should learn my geography better.... I saw Wisconsin and automatically assumed Michigan..

 

[Honeyman]

No and no again...not near enough hp for a 30ft boat.

 

[wayneR]

Someday you might want to sell this boat and the 8 hp engine will be a real problem. Too small for 30 ft. My lightweight Oday 272 had 15.

 

[tommays]

I moved the Cal with a well pitched 4hp at 4.5 knots and sail on a C&C 35 with a14hp beta in all kinds of weather

It's still pretty small To do that much work on and install

The standard Cal29 direct drive A4 prop. Is 12 X 8 which is a tiny prop for 20+hp

 

[Steve Dion]

Hey! Look at it this way. Many race boat have no motor at all. If you can sail in/out of the harbor why do you need a motor at all.

You just need to time your entrance/exit to the harbors or any place that it may take extra power.