Too much HP??

[Triton II]

Re: Too much HP??

My 15.5ft alloy cuddycabin has a max hp of 80. It'd easily cope with a 300lb motor... its max transom weight is 395lbs. So maybe you should take the transom weight max into account more than the max hp... just don't have an accident! Hope Chris-Craft come through for you with the info you need.

 

[dajohnson53]

Re: Too much HP??

Originally posted by Mnemonic:<br /> According to the USCG Backyard builders formula:<br /><br />Length - 15'<br />Width - 6 '<br />Multiply width x length = 90<br /><br />Transom Height 20" x 2 = 40<br />Add it all together and subtract 90 is the max allowed HP.<br /><br />So that means the max HP will be 40 HP on this boat? Thats a little crazy going more than double.

The max according to the formula is actually 90.<br /><br />The calculation is:<br /><br />Length (15) X width (6) = 90 this is the "factor" for your boat.<br /><br />For factors > 52, and transoms of 20 inches or greater, and remote steering you <br /><br />multiply factor X2, then subtract 90<br /><br />90 X 2= 180<br />- 90<br /><br />=90 this is the max. HP for your boat according to the USCG guidelines.<br /><br />[this is where you made your error - you don't multiply the transom height by 2 then add everything together and subtract 90. The transom height is only used to determine which formula you use. It isn't part of the formula]<br /><br />There are some other assumptions - you should read the guidelines. Bottom line though is hopefully Chris Craft will tell you what their opinion is, and you should probably follow it. If that isn't available, what I'd do is use the USCG formula and my own judgement whether its safe.<br /><br />Good luck

 

[cobra 3.0]

Re: Too much HP??

You don't have to ride it full throttle everywhere you go. You could even limit gas cable travel to a speed which you feel safe in if it becomes an issue (which I doubt).<br /><br />Was there ever a plate on this boat? Providing there was never a plate on your boat due to its age, the formula is the way to go.

 

[Mnemonic]

Re: Too much HP??

Wow, thanks for all the great responses guys !<br /><br />D. - I guess i'm retarted when it comes to math... so at least we know if i built her in a backyard she would be able to take a 90.. I will be talking with chris craft today, someone on biberglassics.com identified my boat as a 1964 Chris Craft/Thompson Corsair Sunlounger XL155 - so at least i know what i'll be asking for.<br /><br />Thanks again guys

 

[Straightup]

Re: Too much HP??

Have the Rinker 15' bowrider in my garage. Model V153. Placard states max HP at 90. <br /><br />Jeff<br /><br />A tip that I've learned from the Remote Controlled Aircraft hobby is that overpowering usually isn't worth it. Our planes have a huge power to weight advantage over full scale already, yet some guys really hang some big engines on their birds. Once you get a little ways over the recommended engine size you really start to see the weight effects thus shooting yourself in the foot. The same holds true for boats.

 

[Mnemonic]

Re: Too much HP??

Straightup - Cool, I hope Chris Craft tells me the same... if i ever get in contact with them - I learned something about CC today - they dont do well with returning phone calls or emails.<br /><br />Honestly if a 40-60HP motor was as cheap as what i am getting for the 90HP I would probably go with that... but i talked the guy down to $500 today..

 

[Mnemonic]

Re: Too much HP??

Got off the phone with chris craft... They said the max HP on my model is 90HP! WhooHoo! Just got off the phone with the guy selling the motor and I'm pickin it up tommorow <br /><br />Thanks again all!

 

[dajohnson53]

Re: Too much HP??

Man, sounds like fun. Let us know how she goes!

 

[AMD Rules]

Re: Too much HP??

Nice...lucky you! Don't forget to take pics.... gotta love them tall skinny TOPs.

 

[AntsGrady]

Re: Too much HP??

NICE...that boat is gonna move!!

 

[Marauderk]

Re: Too much HP??

My 15' Ebbtides has a max rating of 90 hp

 

[Mnemonic]

Re: Too much HP??

As requested - Pics of the motor - soon to be on the boat.<br /><br />

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<br />Is this bad? <br />