Transom Wedges

[Marley]

Hi Guys

I have a 16 ft aluminum with a 90 Merc. I sometimes have issues with proposing especially with heavier people in the back seats. I also don’t seem to have enough trim range to get the bow down when needed. I am thinking transom wedges might be the solution as the cavitation plate of the motor seems to be in the correct spot when running. Thoughts?

 

[Pineapple Express]

Can you redistribute weight in the boat? Move the battery or fuel tank further forward? Change seating positions?

 

[Marley]

Fuel tank and battery are a bit hard to move. I do have a live well in the front that if I fill with water definitely helps but trim range is still limited even lightly loaded.

 

[ship happens]

Transom wedges work real good. Used them lots. Especially on custom aluminum boats where the transom degree is off. More the merrier. Can always trim up!

 

[Marley]

Transom wedges work real good. Used them lots. Especially on custom aluminum boats where the transom degree is off. More the merrier. Can always trim up!

Ok thanks. That’s what I thought but wanted some expert advice to make sure there were no hidden issues. Appreciate it.

 

[Squire]

Transom wedges work real good. Used them lots. Especially on custom aluminum boats where the transom degree is off. More the merrier. Can always trim up!

^This^
I added wedges and moved the outboard up one hole to deal with porpoising at low planing speeds (3400 rpm, 26 mph). I trim right in to keep the bow down for a quick hole-shot and trim up to the sweet spot as I level out.

 

[Marley]

^This^
I added wedges and moved the outboard up one hole to deal with porpoising at low planing speeds (3400 rpm, 26 mph). I trim right in to keep the bow down for a quick hole-shot and trim up to the sweet spot as I level out.

Thanks for the insight that is exactly what I was planning to do. Glad to know it worked out for you.

 

[Max123]

On light boats porpoising seems like a common issue. One thing I'd suggest is to confirm your motor is mounted high enough. A motor that is too low will definitely add to porpoising issues. A hydrofoil can also help because it provides some stern lift - but i'd only add if you are sure the mounting height is right.

The way to tell if a motor is mounted right is to get it up on medium/fast plane -say 25mph, then look over the transom and see if the anti-cavitation plate is visible and cleanly skimming the surface. If its buried in the water, its too low. If you are getting a V spray off the motor, its too low.

 

[Marley]

On light boats porpoising seems like a common issue. One thing I'd suggest is to confirm your motor is mounted high enough. A motor that is too low will definitely add to porpoising issues. A hydrofoil can also help because it provides some stern lift - but i'd only add if you are sure the mounting height is right.

The way to tell if a motor is mounted right is to get it up on medium/fast plane -say 25mph, then look over the transom and see if the anti-cavitation plate is visible and cleanly skimming the surface. If its buried in the water, its too low. If you are getting a V spray off the motor, its too low.

I had a look last time I was out and the cavatation plate looks ok, maybe a little low. I am going to add the wedges and bring the motor up one hole at the same time. See how the combination affects handling.

Thanks for the advice

 

[seachicken]

Check your WOT too, had a 15.5 K&C family boat that had been set up by someone else. Used to porpoise until I got the right prop on it.