Max HP ?

[HPBB]

I have a Sea Nymph GLS 175. It had a 75 HP motor on it. Well, I blew up the power head the other week and rebuilding its out of the picture right now. I have been looking at some used motors and have a question. The max recomended HP for my boat is 100HP. I am looking at 3 motors right now, all are made by the same co. and are the same style , look identical and weigh the same and are almost the same price.  one is a 90 HP , 115HP and a 140HP. The 115 seems to be the better motor  and I like the power of the 140, but would they hurt the boat? I mean all the motors wiegh the same. I can see going up to a 150hp V6 would be to much weight, but  these are 4's. would it be legal?

Jim

[Matt Fly]

USGC rates all boats for motor sizes.       I do know that most of the trails I fish will disqualify you for running an oversized motor that doesn't not meet the USGC Label plate that comes with all boats now days.

Max HP rating plate says 100HP, then its 100 horses Max.    

I understand that motors and technological break throughs have a lot lighter motors out there to replace the older heavier motors, but speed and stability are key concerns as well as weight distribution.

The USGC is the one who could best answer that question of legalality.

Matt

[senile1]

Matt is right.  It isn't the weight of the higher horsepower motor that is the major concern.  The transom of the boat is only built to handle so much torque from the motor.  When your prop "grabs the water" a force is received by the transom where the motor is attached.  I would not exceed the horsepower ratings.  If you're into cars or motorcycles, apply the same reasoning.  If you place a much higher powered motor into a frame designed for much lower power on a motorcycle, without reinforcements and gussets, the frame will flex to the point that the handling on the motorcycle is completely ruined.  

[Way2slow]

Well, I'm kinda the renegade when it comes to over powering a boat.  Don't think I've ever had more than one or two that weren't over powered and they usually got over powered rather quickly.   Back in the 60's I had a 16' Allison with two 135BHP  mercs.  I've had a 15' Procraft rated for 85 hp with a 200 EFI merc on the back.  I've had several 17' boats with 200 - 250 hp on them.

A 18.5 Stratos rated for 175, running over 300 hp.  I've never even looked to see what my 20' Javelin is rated for but when I get that wild hair, I put one of my 300+ hp motors on the back of it just to raise H*** and tick those Tritons off.  

The transome is built to withstand a whole lot more stain and force that what that extra HP puts on it.  Hitting an underwater obstacle at 40 mph and having the motor knocked out of the water places a 100 times more stress on the transome than that little extra hp hung back there.

The three keys things you have to watch out for when over powering a hull is:

1.  The weight,  adding much more weight than the class motor the hull is designed for make it sit deeper in the back.  If too deep, it's too easy for wakes and rough water to wash over into the back of the boat when stopped and fishing.  NOT GOOD.

2.  The insurance.  If you are required to carry insurance on your boat, forget it.  More than about 5% over and they will not insure it and will not pay off a claim if they find out it is over powered.

3.  State laws.  Some states, (a lot of the northern states) have strict laws against over powering and have very healthy fines if caught.  

[cart7t]

As stated in summary:

1. Check the legality in the state you're in. I've never had waterpatrol officer check my engine against the USCG plate.

2. Check with the Insurance company.

3. If you wanna fish tourneys forget about overpowering.

4. If the engine you're wanting to go with is significantly heavier than the average weight of motors recommended for your boat you will sit stern heavy in the water.