Re: make a 50hp out of a 40hp
I think there also needs to made a distinction between hanging too *big* a motor for the transom (or boat size) and the HP issue. I make a distiction here that Willy doesn't.
<br /><br />And then we get into "How old is the boat? Is that infamous "sticker" crankshaft HP or is it propshft hp??"<br /><br />In the case of the 99ci "direct charge" inlines they came in 90/115/135/140/150 hp versions as rated at the powerhead. Depending on the power trim they ALL WEIGH THE SAME and for the most part have about the same bottom end torque on the hole shot. (Speaking to modern boats the most propshaft hp those 150's produce is about 135)<br /><br />IMHO you can hang a 99ci 1500 on anything you could origionally hang the 99ci 90 on. Same motor, more top end. Ditto the 40/45/50's of old.<br /><br />In my opinion getting the most hp out of the correct size/displacement motor for your boat isn't where the real serious risks come in. It's when you put a bigger motor on that was ever intended to be there. At the point where the boat faces a loss of controll from excessive chinewalking or risks blowover... you went too far.
<br /><br />To use my 2000 Seaswirl as an example....<br /><br />It came with a 115 Jonnyrude and was the hull stiker says Max 140. Being a 2000 this is all propshaft ratings. I hung a 1988 propshaft rated Merc 115 on it. (lighter on the transom for openers)<br /><br />I'm in the middle of building a "one off" 1500 ADI powerhead for it. Even with every trick in the book thrown at it, I'll be lucky if it ever exceeds 140 at the propshaft, so my *reality* is that I'll be within the spirit of the sticker. But it would be kind of silly for me to resticker the motor to a 1500 when to anyone else *but* someone of my level of expertise it comes off as a 115. Why invoke all the questions should something ever happen?<br /><br />Some of these questions about upping power and overpowering a hull are best left to the "Scream & Fly" boards. Those guys specialise in just that kind of stuff. <br /><br />The best single safety step (aside from all the rule book stuff)) is to stay off the water (or away from the traveled areas)on the holiday weekends when all the twice a year yahoos come out and do some very, very, strange things on the water. <br /><br />The next best safety thing is to TROLL if it's dark or you've had anything at ALL to drink (or both). My cousin was killed by a drunk boater, I was almost run into at night by one, I was stopped - light on) Nothing scares me more than a 300hp bass boat with a case of beer loaded. <br /><br />Next is a wrist mounted kill switch and a worn lifevest of sufficiant speed rating for your boats speed if you're gonna hammer it.<br /><br />But I rammble..........<br /><br />-W
