HELP!!!!Need BOAT TO GO FASTER!!!

[bruce1962]

I have a 1997 80 hp yamaha, other than changing prop how can I get more speed? It's on an 18 foot sea ark and only runs 20 to 25 mph has tilt & trim & hydraclic jack plate.Does anyone have any knowledge to give about making the boat go faster? Any answer might help!!!!!!

[russfer]

Sorry to tell you, but on an 18 foot boat I think you are doing quite well with a 80hp motor

[bumperfood]

I am assuming that your engine is in excellent condition, and running at peak horsepower, and your rpm at top speed is a specified. If this is the case you are going as fast as you are going to go with what you have. If your rpm is not where it should be at top speed, and you wish to retain the same propeller you need to have the least amount of wetted area on the hull as possible when at speed. Once you achieve that, you need to make that area as slippery as possible, high gloss paint, wax etc help. You can also lighten the boat as much as possible, how you do that is up to you, but every pound will help. If you decrease the aerodynamic drag, by removing any canvas covers etc. you may gain a slight improvement. Your jacking plate can help by raising the engine so that less of the leg is in the water at speed, but you need to make certain that you don't compromise engine cooling. Any other protuberances beneath the transom-depth sounder skimmers etc, also affect the drag on the hull.

[ohsoslow]

I have to agree with russfer on that. But, I have been doing a bit of research into performance modifications for outboards, and the most common mod seems to be changing the reed valves for performance ones, boyeson etc.

The other obvious thing to do, is make the boat as light as possible!

I'd be guessing for that size boat and motor, the jacking plate is probably just adding weight, I can't see it doing all that much for performance.

On my old boat, I put one of those "hydrofoils" on the motor, to help it get up on the plane, and then raised the motor up on the transom. This effectively meant I could run the motor high, while still being able to get on the plane with a load on. Once up on the plane, the hydrofoil was out of the water, minimising drag. (I had a 15ft boat with a 70hp)

Hope that gives you a bit to research!

[davepjr71]

Is the anti vent plate at the top of the water when you are trimmed out or buried in the water? The plate should be just above the top of the water surface or you are loosing performance. Check out this link for an explaination.

Propping correctly & how to test props.....