Super User WIGuide Posted February 27, 2017 Super User Posted February 27, 2017 @Peter Eikenberry Just here to pick your brain, what is the formula they use to come up with a horsepower rating? I know weight has a lot to do with the rating, but with the way outboards are made these days using the same blocks for multiple motors it seems like there must be more too it. Say a boat is rated for a 200, but the 225 and the 250's tip the scales at the same weight, so what warrants one over the other? Quote
Super User A-Jay Posted February 27, 2017 Super User Posted February 27, 2017 1 hour ago, WIGuide said: @Peter Eikenberry Just here to pick your brain, what is the formula they use to come up with a horsepower rating? I know weight has a lot to do with the rating, but with the way outboards are made these days using the same blocks for multiple motors it seems like there must be more too it. Say a boat is rated for a 200, but the 225 and the 250's tip the scales at the same weight, so what warrants one over the other? This will get you started . . . . http://newboatbuilders.com/pages/hp.html Here is the link to Title 33 NAVIGATION AND NAVIGABLE WATERS PART 183 BOATS AND ASSOCIATED EQUIPMENT Subpart D—Safe Powering. It applies to monohull boats less than 20 feet in length, except sailboats, canoes, kayaks, and inflatable boats, that are designed or intended to use one or more outboard motors for propulsion. http://newboatbuilders.com/pages/33CFR_HP.html Have fun with that. A-Jay 1 Quote
Super User WIGuide Posted February 27, 2017 Super User Posted February 27, 2017 24 minutes ago, A-Jay said: This will get you started . . . . http://newboatbuilders.com/pages/hp.html Here is the link to Title 33 NAVIGATION AND NAVIGABLE WATERS PART 183 BOATS AND ASSOCIATED EQUIPMENT Subpart D—Safe Powering. It applies to monohull boats less than 20 feet in length, except sailboats, canoes, kayaks, and inflatable boats, that are designed or intended to use one or more outboard motors for propulsion. http://newboatbuilders.com/pages/33CFR_HP.html Have fun with that. A-Jay Interesting stuff! Makes me wish my boat would have been made just a hair wider to accommodate a bit more motor even though I may have found a "legal" loophole to do so haha. It's interesting their rating formula doesn't accommodate for engine weight. Quote
Peter Eikenberry Posted March 9, 2017 Posted March 9, 2017 Sorry I haven't been back to this forum in a while. The formula is based on boat centerline length, transom width and transom Height. The weight of the engine is taken into account in the calculation of load capacity and how much flotation the boat must have. But the weight has little to do with the HP rating. The formulas for HP vary depending on the type of boat and whether or not they have remote steering. This was all determined by research done by the boating industry back in the late 50's and 60's. Yeah a lot has changed since then, but the formulas haven't. In the EU they use a maneuverability test and the Coast Guard and the American Boat and Yacht Council have conducted tests comparing the two. They are comparable, and in some cases the formula is more liberal. So it all evens out in the end. Research has been done looking for other methods but none were as good as just using the formulas. Peter 2 Quote
Super User Further North Posted March 9, 2017 Super User Posted March 9, 2017 On 2/7/2017 at 3:28 PM, Way2slow said: My personal feelings are different that most replying. I've overpowered almost every boat I've owned, some massively. For instance I have a modified motor I put on my Javelin R-20, rated for 245hp, that dino's at 326hp off the prop. The boat will run in the lower 80's with full gear, livewells, two people and gas. However, there is the thing about boat knowledge and being a responsible operator. If you own a 1,000hp car that will run 200+ mph, doesn't mean you have to drive it that fast. Now, there are two major obstacles/concerns when over powering one. Insurance, is one, buying a nice boat, usually means financing and that means it MUST be insured. Getting coverage could be a problem, and if you lie about it, it could come back to bite you if you ever needed it. The next is the liability factor. Get in a accident, even if it's not your fault, a good lawyer will have you for lunch and you may be working for someone else the rest of your life. If neither of those are problems, then I see no problem with having what ever motor you want. I don't think Tennessee is one of those states that have laws against it like some states. Some states its a very serious problem if you get caught with an over powered boat. Curious...how would anyone know what the HP of a modified motor is? ...other than the owner or the person who did the work? 1 Quote
Super User Way2slow Posted March 9, 2017 Super User Posted March 9, 2017 The way mine is modified, using almost all factory parts, without a knowledgeable person pulling the heads off and checking it, it's not very likely anyone could really tell. If you lift the cover, the only obvious thing you see that is not factor are the eight leads (one in each cylinder and two in the exhaust adapter) going to the thermocouple for pyrometers in the exhaust. I could leave those off also, but pistons are about $100 each and a pain in the butt to replace and on a cool morning it can pop one before you say don't do it. To keep from changing jets every time the temps change, I just monitor the egt's and back off slightly when needed. Some people like to show it's a modified motor by installing the racing flywheel, velocity stacks, open exhaust, and all kinds of other stuff that adds a lot of show, but not much go. You can hear them coming a mile away. I prefer the "sleeper" look. I don't spin mine enough rpm to need a racing flywheel, and velocity stacks would add very little horse power at 6,500-6,800 rpm but make a ton more noise. The neat part about it, if you've got deep enough pockets, you can take a 200hp etec to 350hp and it still look stock or make it a 450+ horse monster motor. https://www.youtube.com/watch?v=hxl2ldHybHE 1 Quote
Super User Further North Posted March 9, 2017 Super User Posted March 9, 2017 1 hour ago, Way2slow said: I prefer the "sleeper" look. We think alike. Every fast car I've owned looked just about exactly like the "normal" variant, unless you knew what to look for. Most people - including law enforcement - have no idea. That kept people's - including law enforcement - focus on the extroverts who had to brag about and show off their fancy toys...and kept me under the radar. Quote
Super User WIGuide Posted March 9, 2017 Super User Posted March 9, 2017 3 hours ago, Way2slow said: The way mine is modified, using almost all factory parts, without a knowledgeable person pulling the heads off and checking it, it's not very likely anyone could really tell. If you lift the cover, the only obvious thing you see that is not factor are the eight leads (one in each cylinder and two in the exhaust adapter) going to the thermocouple for pyrometers in the exhaust. I could leave those off also, but pistons are about $100 each and a pain in the butt to replace and on a cool morning it can pop one before you say don't do it. To keep from changing jets every time the temps change, I just monitor the egt's and back off slightly when needed. Some people like to show it's a modified motor by installing the racing flywheel, velocity stacks, open exhaust, and all kinds of other stuff that adds a lot of show, but not much go. You can hear them coming a mile away. I prefer the "sleeper" look. I don't spin mine enough rpm to need a racing flywheel, and velocity stacks would add very little horse power at 6,500-6,800 rpm but make a ton more noise. The neat part about it, if you've got deep enough pockets, you can take a 200hp etec to 350hp and it still look stock or make it a 450+ horse monster motor. https://www.youtube.com/watch?v=hxl2ldHybHE I definitely like the sleeper look as well. I wish I had money as I'd have a few things hopped up. I'd really like to get a Ranger Z 518C which is rated for a 200 and put a Yamaha SHO on it. With nothing more than an ECU reflash they can be bumped to 300 HP and if you change the rev limiter they can be up into that 350 hp range. I just saw a video of a build of one on youtube the other day but I couldn't find it again. Quote
Super User Way2slow Posted March 9, 2017 Super User Posted March 9, 2017 The engine Dave Bush has on the dino is the one I was building before my hand surgery. Just the parts to build that are expensive. That one is running an after market fuel injection, custom billet heads, a special set of sleeves and pistons he sells for about $1,200. When you buy the custom sleeves, you can also get a guide sleeve for porting the block. Then is about 100 hours of work with a die grinder by someone knowing what to do to prepare the block. Like I said, if you had to pay someone to do all the work, you would need some deeeeeepppp pockets. Quote
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