12' Aluminum V-Hull - Issues porpoising and planing

[Blair Charbonneau]

Good Evening Gents!

I have an older 12' v-hull princecraft

I reached out to princecraft to try and figure out the exact year but their records don't go back that far.

It is rated for Max 15 hp and max weight of 710 lbs.

I recently upgraded from my 6hp 1975 evinrude to a 2024 tohatsu 9.8
I couldn't get on plane with the 6 hp and wanted to have a bit more speed to get to my fishing locations.
I realize the older 2 strokes were much lighter than the new four strokes. Could this be the main contributing factor?

The issues I am experiencing with the 9.8 (80 lbs) - and only myself in the boat (180lbs)

- The boat catwalks like crazy at low speeds. So much so that it's close to taking on water at the stern. I have tried all the trim positions and it seems to make no difference.

-The boat planes out once I get over half throttle or so. But, at this point it starts porpoising. Again, this is constant on all trim positions.

My fix - I put 2 large tree stumps in the bow as I had just finished cutting down some birch tree.
This fixed both issues.
I got up to 32 km/hr - nice smooth ride.
However, it is very cumbersome to have to move these in and out when I do have a passenger. Also, they aren't super stable and vibrate around a bit.

My questions

1. Is my motor and myself too heavy for this boat?

2. Is there a better fix than putting weight in the front? I will opt for bags of sand or gravel if this is the best option.

3. Am I missing something completely?

I can provide some pictures If necessary

Thanks Folks!

 

[airshot]

Often a problem with small lightweight tinnies. You need the trim in to get up on plane but once you get there, to much trim in causes porposing. Power trim would help greatly but not many small motors have it. Move your load forward like the fuel tank, battery, anchor, tool box and anything else you have to move. You might have to make storage areas up front for these items. Some folks add an extension on the tiller handle so the operator can sit further forward.

 

[Stand Up]

I keep my anchor, safety gear that's in a Pelican case and a few other things up front. That keeps the boat on plane at speed.
It must look funny with 2 tree stumps in the boat while fishing. Perhaps there's a funny story here.

 

[Boosh]

Don't those hydro fins devices help with porposing? Thought I saw a post long ago about people using the fins for that issue

 

[thill]

Don't those hydro fins devices help with porposing? Thought I saw a post long ago about people using the fins for that issue

Yup. They work pretty well too

 

[Sinkingfast]

I used a simple planning plate like Paratrim. I have used the plastic foil ones and like the simple plate better. It helps a lot. The ones i made myself using aluminum plate worked best.