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| Author |
Message |
    
Mike Haworth
Visitor
| | Posted on Wednesday, November 29, 2006 - 04:33 pm: | 
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Hi Guys! I have a small 13' dual-cockpit aluminum runabout, originally an outboard, but I have come across an old atomic 4 with direct drive in pretty good shape, and am seriously considering converting to full inboard. There is plenty of room, and moving the weight distribution forward towards the center of the boat is really appealing, as the boat is driven from the rear cockpit on the left-hand side, and tends to be really stern-heavy with an outboard hanging off the transom.
My question is would a 30hp atomic 4 be a viable candidate for this conversion? I am not familiar with the performance of this particular engine, and am not sure if it would have the horsepower, torque, rpm's to plane a small boat like mine, or is it just good for moving sailboats around when theres no wind?! Any wisdom regarding this would be greatly appreciated!
Thanks.
Mike. |
miro
Senior Member
Username: miro
Post Number: 249
Registered: 11-2001
| | Posted on Thursday, November 30, 2006 - 12:53 pm: |
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I suspect that you'd never get it up to plane with that engine. There are performance curves in Weston Farmer's book ( From My Old Boat Shop) that shows the HP vs speed for various hull shapes. The increase in HP needed is spectacular once the terminal hull speed for a displacement hull is reached. And even if you did get it up on a plane, you'd probably be going flat out , full throttle, burning a whole lotta gasolne and making a whole lotta noise.
These engines were designed for slower moving boats, where the captain and passengers enjoyed the passing scene and engaged in thoughtful conversations about old engines.
Slower is better.
miro |
bruce
Senior Member
Username: bruce
Post Number: 129
Registered: 07-2002
| | Posted on Thursday, November 30, 2006 - 09:55 pm: |
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Mike, Are you describing a boat built by Feathercraft-dual cockpit-radical tumble home?? Try putting some sand bags toward the front when piloting alone-trim your outboard to bring the nose down. This sounds like a lot more fun as an outboard boat-nix the Atomic Four plan IMO. |
Mike Haworth
Visitor
| | Posted on Thursday, November 30, 2006 - 04:44 pm: |
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Thanks for the info! I'm not completely discouraged. I have been told that originally my Lone Star Admiral was powered by a 25hp Johnson. Although speed would be great, its possible that it was never more than a picnic cruiser. (I much enjoyed the mental image of cruising around discussing old engines) I have been (slowly) deciphering different websites relating to performance curves. Will keep you posted
Thanks again.
Mike |
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