Speed

[formulafisher]

Hey everyone i have a 1976 forumla 233 center console. I love the boat it has a custom built tuna tower and rupp 20' outriggers. The only problem is the boat wont get out of its own way. Its powered by a 351 ford with about 400hrs on the motor. the boat weights around 4500lbs maybe a little more. Any suggestions on how to get some more speed, anything would be a help. Right now it tops out at around 27mph and cruises at 18moh at 3000rpm. Thanks

 

[f_inscreenname]

Re: Speed

18' Larson I/O 351W. Cockpit speedboat. Probably weighed half of yours and it toped out at 47mph. More speed? Make sure the bottom is clean, tune up, rebuild or bigger motor. It depends on how much you want to spend.

 

[55Crestliner]

Re: Speed

I hate to jump on your post, but I've just got to know - why is it that I hear on here about bass boats going close to 70mph if the 18ft Larson with a 351 is only going 47? Is it just a weight issue? How much power are either of your 351's making? There are a lot of variables with any V8, some only make 150hp, while others will make 400 or more.

 

[cuzner]

Re: Speed

Do you know what size prop you have? It may be your under proped. 18 mph sounds a little slow at 3000 rpm. Whats your tach read at wot?<br /><br /><br /> Jim

 

[f_inscreenname]

Re: Speed

55crestliner<br /> Weight is it along with the shape of the hull. A fully loaded bass boat probably weighs under a thousand pound with out the motor. It has a flat hull made to go on flat water. My old boat was a heavier deep V style boat with a full interior then add the weight of the motor and outdrive, deck etc and you go a lot slower.

 

[formulafisher]

Re: Speed

The boat has a 15 1/2in diameter prop im not sure of the pitch and i was told the engine made 260hp when it was new.

 

[kcccsryan]

Re: Speed

I have a 1986 21ft Formula(206 Thunderbird) and it is heavy also. 350 magnum engine-260hp.<br />I use it for skiing in fresh water.<br />21 pitch prop 14 1/4 diam w/alpha 1 outdrive(aluminum)<br />3500 rpm approx 35 mph<br />4600 rpm(WOT) 53.8 mph by gps<br />I could probably get a couple more mph w/ stainless steel.<br /> Tried 19 pitch and too many rpm but out of the hole fast. 23pitch not enough wot 4100rpm<br />Hope this helps.<br />Kevin

 

[cuzner]

Re: Speed

The pitch determines how much water the prop will move thru (in theory).i.e., a 21p prop will move thru 21 inches of water per revolution. I have a searay sundacer with a 210 hp 5l engine,maybe a little lighter than yours. With a 17p 15.5 inch prop I cruise at 26 to 28 mph at 3100 rpm.The reason I think it may be a prop issue, (low pitch)is the speed your getting at 3000 rpm.There MAY be reasons for a low pitch prop if you have one. Before you invest in a new prop you may want to borrow one first to test how your boat responds. Good luck and keep posting.<br /><br /><br /> Jim