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-   -   What size motor for a 20ft trailer sailer? (http://www.sailnet.com/forums/gear-maintenance/81934-what-size-motor-20ft-trailer-sailer.html)

CoasterNZ 12-20-2011 06:17 AM

What size motor for a 20ft trailer sailer?
 
What size motor for a 20ft trailer sailor? Should be a simple question, but maybe not.. The national trailer yacht federation stipulates a minimum of 6 HP, but I'm wondering if I'm out there in the poo one day in 30 knots, whether 8 HP could be wiser?

But a light motor is good as it will get put on and taken off lots, and is easier for everyone to raise and lower on the adjustable transom, which the current 9.9 HP Suzuki isn't. Wondered about 4 strokes - heavier but cleaner, more efficient, quieter (vibration?) 6 HP 4's tend to be single cylinders and haven't heard wide praise for them. The propeller pitch is the other consideration - any simple suggestions?

tommays 12-20-2011 10:09 AM

A 4HP with the high thrust prop is going to be fine because you wont be able to keep and outboard prop in the water if you let the sea state get above point X

WanderingStar 12-20-2011 10:18 AM

The old formula was 1hp/500lbs. Four horse should be fine. I rowed my 20' keelboat, then used a 45lb thrust trolling motor. Neither method worked into the wind, but then I just sailed.

BarryL 12-20-2011 10:33 AM

Hello,

when I had a Catalina 22 I used a 4 HP motor and I never wished for more power. The boat weighed about 2000 lbs, so I would say that WanderingStar's formula is correct.

Lastly, a long shaft is more important than more HP from a short shaft. A big motor that comes out of the water in waves / chop won't work as well as a 4HP that is in the water when you need it.

Barry

zz4gta 12-20-2011 03:39 PM

I use 3.5 on a 25' 3000 lbs boat. Works just fine. In a sea way, an outboard ain't gunna move you anyway. Hope there's wind, and sail in.

kwaltersmi 12-20-2011 04:49 PM

I agree, 8hp is overkill to be sure. Cavitation becomes a real issue when things get snotty and you have to motor. Better to avoid the snot or learn to sail in it.

MarkSF 12-20-2011 06:08 PM

Quote:

Originally Posted by CoasterNZ (Post 808628)
What size motor for a 20ft trailer sailor? Should be a simple question, but maybe not.. The national trailer yacht federation stipulates a minimum of 6 HP, but I'm wondering if I'm out there in the poo one day in 30 knots, whether 8 HP could be wiser?

But a light motor is good as it will get put on and taken off lots, and is easier for everyone to raise and lower on the adjustable transom, which the current 9.9 HP Suzuki isn't. Wondered about 4 strokes - heavier but cleaner, more efficient, quieter (vibration?) 6 HP 4's tend to be single cylinders and haven't heard wide praise for them. The propeller pitch is the other consideration - and simple suggestions?

I had a Tohatsu 3.5hp 4 stroke on my trailer sailer and it was a great little motor. Sipped fuel, reliable starter, good power. I'm sorry I sold it, it was way better than the Suzuki 2.5 I have on my inflatable dinghy now.

I never noticed much problem with vibration. I tended to lock it dead ahead and steer with the tiller, so I was never holding onto it for long.

As we are likely to see more bodies of water closed to 2 strokes, I think getting a 4 stroke makes sense if you're not too sensitive to weight. 10 or 20 extra lbs isn't going to bother you as much as it would with an inflatable dinghy.

I bought the Tohatsu as, at 43 lbs, it was a good tradeoff, power vs. weight.

bjslife 12-20-2011 09:11 PM

I had a 9.9 Johnson long shaft on my 1969 Venture(mcgregor) 24' and never worried about tide or current. It was easy to lift also.

CoasterNZ 12-21-2011 04:08 AM

Thanks for that - good advice. I'll stick to long shaft.

High thrust - can anyone give me an idea of the dimensions and range of pitch ratio I should look for in a prop?

danr620 12-21-2011 09:25 AM

motor
 
Coaster,

I have 4 hp mariner on my 21 ft, weighs 1400 lbs and rarely need much throttle. I don't sail in the sea, but can't imagine it wouldn't be enough if prop stayed in water.

good luck

Dan


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