Correct HP Outboard

Suggestions, concerns, and what is the correct power plant for your Thompson.

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Posts: 11
Joined: Sun Jan 16, 2011 1:50 pm
Location: Charleston, SC

Correct HP Outboard

Post by carsonphoto »

It's been a while since I have posted on here.
I have a question about horsepower.
I restored a 17' 1959 Barbour Silver Clipper lapstrake runabout a while back and purchased a 1971 Johnson 60 HP outboard.
The Johnson has been nothing but trouble, and I am looking to get something newer and dependable (I'm kind of over trying to keep a "vintagey" looking motor on the transom and need dependability).
Additionally we have moved, and now instead of boating on a calm inland lake, I am boating in the Charleston SC area, which has some wicked tidal currents!
Basically, you can be dragged onto the rocks in minutes if your engine quits!
So anyhow, to get back to my question, what size HP engine can I use and still get good performance?
I would like to get something smaller (less HP) and lighter.
What HP were these type of boats originally rated for?
Would a 25 - 40 HP motor be sufficient?
Bill Dunn
Posts: 95
Joined: Wed Jan 28, 2009 7:34 pm
Location: Wisconsin

Re: Correct HP Outboard

Post by Bill Dunn »

I have a 1959 Thompson Sea Lancer, which is 17 ft. It is rated for up to 90 hp. When I first got it , it had a 1963 Merc 850 in-line 6 cyl. The boat handled it very well with a top speed of about 34 or 35 mph. The motor weighed about 250 lbs with power trim. I have since had to replace the transom because of a bout with "cancer". The new one is much stronger than the original, and I ran across a deal on a 1977 Merc 1150. The motor weighs a little over 300 lbs, and the boat handles it just fine. I was interested in the same thing as you, and this motor is more efficient, dependable, and cheaper to maintain. I gained about 5 or 6 mph, but I am normally cruising at about 30 mph anyway. In your situation, I would be concerned with under powering the boat. You will be on some potentially big water and you want to have enough power to get you where you want to go. I personally would suggest at least in the 70 to 75 hp range. If you have a few people in the boat anything smaller might have a problem planing out. On big water, you don't want that problem.
Just my opinion,
Bill Dunn
All Dunn ll
'59 Sea Lancer
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