Theoretical MPH

[Dhadley]

Re: Theoretical MPH

Thats what the "wheel" does that I use. It's all based off of slip. Its amazingly close.<br /><br />When in doubt....trim it out!

 

[Spidybot]

Re: Theoretical MPH

Dave<br /><br />Good idea. I did think about it as slip is different from hull to hull. Another joker is, that different prop makes also slips differently so it will always end up as 'close to' the fact.<br /><br />Which, by the way, the sheet does even now.<br /><br />The degree of 'stiffnes' in material affects slip greatly. Some used materials actually change shape when under load to make the prop act as lower pitch until planing.<br /><br />The sheet is open code, so any improvements from you guys are most welcome.

 

[MGuckin]

Re: Theoretical MPH

This formula will never be totally accurate. I took 2 existing formulas and made them work together.<br />Flexing of the wheel will vary too much to form a constant that would work with types but this does give you an average. Trim will compensate for the rest.<br />I would imagine every marine service facility has the wheel or similar that Dhadley is referring to.<br />I wrote it for the "Newbie". <br />I used to use Michigan Wheel's site for this.<br />If anybody can improve on it, by all means, please do so.

 

[Bry21317]

Re: Theoretical MPH

Can anyone tell me about the weight of my Bayliner or where to find it? I is an 88 19.5 Foot Capri. I have a force 125 HP engine on it, with a 13.25x17 pitch Hustler prop. I am trying to figure out what the MAX speed would be by this formula. I am running about 4900 RPMS now at about 40mph or just a hair over (Garmin GPS12XL).<br /><br />The bottom of the boat has some scuffs and and unsmooth spots that I am planning on fixing by refinishing.<br /><br />Thanks,<br />Bryan Cox