prop, motor, boat ride relationships?

[woody9768]

I have a 14 foot aluminum boat. It has an olde hull design, but I'm using a 1989 mecury 20 hp 2 stroke to push it along. It does quite well out of the shot and planes nice up to 3/4 the throttle speed. When I open the motor up to full throttle, the nose drops back into the water and plows. I have affixed a porpoise fin to the moter, and I have changed the agle of the engine on the transome through every hole option available on the motor. I have experimenteed with the depth the motor is in the water and liftin git slightly did not help.

Is it a prop angle thing?
Do i have to cut into the transome to drop the motor deeper inot the water?
Do I need to get a fat chick to ride in the back to keep the nose up?

Any ideas why this coupld be happening, and how do i get it to stop.

 

[steelespike]

Re: prop, motor, boat ride relationships?

More than likely the boat has a hook in the bottom near the transom if you lay a long straight edge along the bottom paralell to the keel you may see it in the last 2 or 3 ft of the bottom.
Could be from poor trailer fit or abuse along the way somewhere.
You may be able to push it out and it will stay if it pops back its called oil canning and you may have to add a support.If the fin is in the water at speed it will probably make things worse and further reduce your speed.

 

[woody9768]

Re: prop, motor, boat ride relationships?

Thanks!

I climbed under the boatwith my trustee level and found one side has a hook. It's located in the area between the transom to the rear bench seat.

There is also a shorter one located on teh other side and it's only about 8 inches in length.

So does anyone have a proper sanctioned method for pounding the hook out of my hull. I have tools, mechanical ability, and heat at my disposal.....all I need is some guidence.

 

[Sea Rider]

Re: prop, motor, boat ride relationships?

Would begin testing trim angle 2-3 hole out from transom individually, with chick at bow to ballance better boat go into full throttle, check if this setting gives a parallel boat on water surface, if so, look at back transom to check where water flow is passing, if passing slight under small plate no need to raise engine. Would be a good idea to installl a induction tach on engine and at wot see if inside min & max rpm stated for that engine, probably you are not propped at the best ?

Full throttle is used to move more weight, plane faster. With a 20 HP will have slight better speed at wot than at 3/4, but don't expect a awesome increase performance. Do you have excesive water splash issues at back or water entering through middle transom inside boat ?

Happy Boating

 

[steelespike]

Re: prop, motor, boat ride relationships?

Thanks!

I climbed under the boatwith my trustee level and found one side has a hook. It's located in the area between the transom to the rear bench seat.

There is also a shorter one located on teh other side and it's only about 8 inches in length.

So does anyone have a proper sanctioned method for pounding the hook out of my hull. I have tools, mechanical ability, and heat at my disposal.....all I need is some guidence.

I think I would try to push it out if its just the skin it may push fairly easily,
keeping it out may be the trick.Perhaps push it with a couple of 2 by fours rigged up to push down either a lever or maybe a jack

 

[Fed]

Re: prop, motor, boat ride relationships?

Pictures of the inside & outside could get you some more suggestions.

 

[Slow Ride]

Re: prop, motor, boat ride relationships?

Have the fat chick sit or stand on the repair so that it doesn't "pop" back! LOL!

Sounds like you have sound advice. Keep us posted! I'm courious?