Should I put a 100HP Yamaha Four Stroke on my 16ft Hewescraft River Runner

[speed_demon]

I have a 1983 16ft Hewescraft River Runner and I'm wondering if it would be wise to install a 100hp Yamaha 4-stroke which I already have. The boat is rated for 80hp max but I've seen people run 115hp but they were all 2-stroke jets. Probably pushing 85hp at the jet and weighing in at about 310lbs. My Yamaha is rated for 100hp but the same motor was renamed 90hp when they came out with the 115 model. It weighs 375lbs which is the same as the 75/80hp model and relatively light for a 100hp 4-stroke. I'm already planning to beef up the transom no matter what engine I use. I'm not only worrying about the power but the weight.

Any help is greatly appreciated.

 

[cyclops2]

Re: Should I put a 100HP Yamaha Four Stroke on my 16ft Hewescraft River Runner

If you are not worried about your insurance coverage in a accident. Go for it.

Not sure about local, county, state or USCG violations. If any.

 

[speed_demon]

Re: Should I put a 100HP Yamaha Four Stroke on my 16ft Hewescraft River Runner

If you are not worried about your insurance coverage in a accident. Go for it.

Not sure about local, county, state or USCG violations. If any.

Someone told me if you exceed the max hp not only will your insurance not cover an accident but you will be considered at fault regardless. Although this sounds a bit extreme I read even if you are docked and someone hits you you are resposible for both boats.

 

[cyclops2]

Re: Should I put a 100HP Yamaha Four Stroke on my 16ft Hewescraft River Runner

I have nothing to do right now.
I will do a websearch of.............Legal risks of excessive horsepower in a boat.

Armchair lawyers will have a field day.

 

[aerobat]

Re: Should I put a 100HP Yamaha Four Stroke on my 16ft Hewescraft River Runner

when weight is not an issue you have to explain the question by yourself. beyond any insurance issues you may encour an unstable ride and trimming problems on the one hand going beyond the max rating, on the other hand you can talk to neighbours what a bullet you have. when interested in a stable ride and safe boating respect the max hp the boat is rated for, when interested in speed stories at the table put anything you can pay and the boat will carry on the transom. its your choice !

best regards

 

[cyclops2]

Re: Should I put a 100HP Yamaha Four Stroke on my 16ft Hewescraft River Runner

Did a quick surf on oversized O B motors ................Useless. All old years & not sure .

1 poster made a EXCELLENT POINT.

Why do ....ONLY O B.....Have a horsepower plate rating ? I / O or inboards do not have them ?

 

[strokersquid]

Re: Should I put a 100HP Yamaha Four Stroke on my 16ft Hewescraft River Runner

I'm wondering about the rating of the engine as well. I have a chance to replace my 100 HP 2st Merc with a 2001 carb'd Yamie 100 HP 4st and I wonder if I will be going down in power or not.

 

[tx1961whaler]

Re: Should I put a 100HP Yamaha Four Stroke on my 16ft Hewescraft River Runner

Did a quick surf on oversized O B motors ................Useless. All old years & not sure .

1 poster made a EXCELLENT POINT.

Why do ....ONLY O B.....Have a horsepower plate rating ? I / O or inboards do not have them ?

Inboards are sold with the motor as a more or less permanent part of the hull. Outboard hulls do not have to be sold with an outboard on it.

 

[aerobat]

Re: Should I put a 100HP Yamaha Four Stroke on my 16ft Hewescraft River Runner

at least in europe I/O boats have an plating with max permitted power as well , further like said the boat is sold with an engine and the manufactures has to take care this engine is right.

 

[cyclops2]

Re: Should I put a 100HP Yamaha Four Stroke on my 16ft Hewescraft River Runner

What makes a O B boat over + 20 feet completly safe with unlimited horsepower motors ? 2-3-4 motors.
Or a 4,000 hp offshore race boat being driven in crowded rivers as a safe boat ? Lots of insurance companies have their risk rates up their back pocket.

Or maybe. They take the under 20' O B premiums to payoff on the PWC & inboard raceboats crashes & law suit payouts ?

 

[sschefer]

Re: Should I put a 100HP Yamaha Four Stroke on my 16ft Hewescraft River Runner

Just gonna hit the high points here ---

Outboards are mounted on the very aft end of the boat. Different weights change the center of balance of the boat. If you change the center of balance by adding more weight you change the way the boat handles and it can become unsafe. In a inboard the center of balance also has a lot to do with engine placement and weight but because it is in a position of less leverage it is not as succeptable to changes in engine weight. If there is a dramatic change of weight in an inboard engine, the position of the engine can be changed to relocate the center of balance to a safe position.

HP ratings for outboards are as much related to weight as they are to how fast the boat can go. As was mentioned before, the HP rating is assigned by the manufacturer to meet a number of requirements. First, if it's under 20' it has to level float. Second, the max load rating has to have a reasonable amount of excess above and beyond the engine weight so that the boat is not easily overloaded. Third, outboard boats are not sold with motors (mentioned above). Any motor above 25 hp or motors with full controls are not sold directly to the public, you must buy them and have them correctly rigged by a dealer. This ensures that an oversized motor is not installed on a boat and is a portion of meeting the manufacturers warranty requirements.

Is it against the law for you to install a motor of a higher hp rating than the nameplate say's. No, however, if there is an accident it would be an easy target for a negligence suit. I ran a hot rod motor on a boat and just changed the cowling decals so it was within the max hp of the boat. Nobody but me knew approximately what the hp was and the USCG never questioned it when I went through a voluntary inspection. In otherwords, if you don't tell them, they have no way of proving otherwise unless it's blatently obvious.

 

[speed_demon]

Re: Should I put a 100HP Yamaha Four Stroke on my 16ft Hewescraft River Runner

I understand hanging more weight off the back will have effects on handling. What I'm really after is if someone is familiar with my boat and if 375lbs is too much and if putting the hammer down with 100hp will cause damage. A max HP rating doesn't really tell me everything I need to know. By that rational I can hang a 1000lb 80hp engine off my transom. To complicate matters further up until 1986 they were rating HP at the crank and my motor is rated at the prop (roughly 10-15% loss) so by that rational I can only run 68hp. The max hp rating almost seems arbitrary and I can only confidently assume it actually means a typical 80hp outboard at the time of manufacture which would be a 270lb 2-stroke. I want to run an Yamaha four stroke but the F80 is the exact same engine with a restrictor plate. Same weight just less peak hp which doesn't do me a whole lot of good asside from legalities. I wish the manufacturer listed a maximum weight.

I'm confused!! In my younger years I would have just installed it and set off to see how fast it would go.

 

[speed_demon]

Re: Should I put a 100HP Yamaha Four Stroke on my 16ft Hewescraft River Runner

Does the coast guard check model numbers or just the cowling? I'm planning on having my cowling repainted and my guy does amazing work with stencils. He can make it look just like a factory F80 but the serial tag is still going to have "F100" in it. I hate to think what they would do if they know you falsified the HP rating.

 

[aerobat]

Re: Should I put a 100HP Yamaha Four Stroke on my 16ft Hewescraft River Runner

i do not think coast guard is interested in a deep search of your "real" power under the cowling. its nevertheless your risk and you have to explain it when you wreck your boat and somebody finds out, especially when somebody gets hurt.

 

[cyclops2]

Re: Should I put a 100HP Yamaha Four Stroke on my 16ft Hewescraft River Runner

Is there a federal, state or local law & fine / imprisonment if you do run over the tag rating?

There may still be insurance companies that will O K over the recommended hp if you will pay a premium. Does anybody know for sure about any ?
Usually money can buy anything out side of the normal. Insurance included.

 

[speed_demon]

Re: Should I put a 100HP Yamaha Four Stroke on my 16ft Hewescraft River Runner

i do not think coast guard is interested in a deep search of your "real" power under the cowling. its nevertheless your risk and you have to explain it when you wreck your boat and somebody finds out, especially when somebody gets hurt.

I think you're right about the coast guard. Depending on where you are in Alaska you definately want to be aware of fish and game. I've seen them run vin tags, pull cowlings, and even heard of requiring dealer inspections on detuned engines. The commercial fishermen are doing some hardcore lobbying to kick us off the Kenai during the late-run sockeye salmon. During july you have to run 4-stroke or DFI 2-stroke and you can only run 50hp on the upper Kenai which excludes the majority of boats. And they enforce fiercly. They haven't been able to eliminate dipnetting but they're making it more and more expensive and troublesome to participate. Kinda went off on a tangent but it honestly pisses me off.

 

[cyclops2]

Re: Should I put a 100HP Yamaha Four Stroke on my 16ft Hewescraft River Runner

Speed demon

Keep saving up your coins. When you have enough of them.
Buy a kneel down racing hydro, O B powered. It is all the power you need while giving injury & death the finger. Very satisfying way of running WOT in a small crowd. Most guys are still around with all the parts working long after they retire.

Buy a racing boat if you need to do WOT. Safer for everybody.

 

[cyclops2]

Re: Should I put a 100HP Yamaha Four Stroke on my 16ft Hewescraft River Runner

Racing O B boats DO NOT have a COURTROOM LEGAL horsepower tag anywhere. Neither do home built boats. Only VIN numbers in some required states.

Check with some Boat insurance companies for what they will allow / cover. Post back since most of us really do not know for sure.

 

[speed_demon]

Re: Should I put a 100HP Yamaha Four Stroke on my 16ft Hewescraft River Runner

Can I put a trolling motor on a hydro?

Don't get me wrong I would like to occassionally pull away from a buddy but I don't need 100hp to do 35mph. The main reason I ask is I already have the motor and this time of year it's difficult and expensive to find another 4-stroke or DFI in Alaska. Nor do I really want to drop another 7 grand.

 

[speed_demon]

Re: Should I put a 100HP Yamaha Four Stroke on my 16ft Hewescraft River Runner

Check with some Boat insurance companies for what they will allow / cover. Post back since most of us really do not know for sure.

I called a geico and state farm. A lady at Geico said "that's not too much over" and said she could write the policy but when I asked if I would be covered in case of accident she didn't have a straight answer. State farm said no. On a small claim I doubt they'd check though.