rodholder vibrations problem

[jwmiller33]

i have 4 rodholders in my boat. its an aluminum boat and i installed them using the block of wood bolted into the side of the boat, then screwed the rodholders into the wood. here are my 4 rodholders in my boat

The problem I am having is when I am trolling with my big motor (1979 35hp Johnson LS tiller), the motor vibrates sometime and that motion is directly transferred to anything touching the aluminum shell of the boat. The vibration comes in little surges and only at certain throttle points, but it happens sometimes frequently when I am trolling (2.0 mph). The way I have these rodholders mounted to the wood that is bolted to the aluminum sidewall is making the vibration travel to my rod and it vibrates so much I can't tell if my lure is running true. This only happens for a few seconds when it does, but it's something I'd like to deal with. I was thinking about adding some type of absorbent material, like a foam pad the exact same shape as the block of wood, and mount that inbetween the wood and the aluminum. Do you guys think this would work to solve the vibration traveling to the rod holder/rod? What type of foam material should I use to do this?

[Surface Tension]

It is caused by removing the bench seats and not adding enough bracing to the hull. All that shaking will loosen rivets and crack corner caps.

Make gussets out of 3/4 plywood. Drill 2" holes in them to lessen the weight and for use as rod storage.

Use aluminum angle mounted to the hull, floor, deck and seat tops for the gusset to mount to. One location for a gusset would be the cut away seat next to the rear rod holders. Question, is that cut away section of seat securely? If not you'll need to stiffen it up. There you could go on top if its stiff enough or go along side if it down to the floor and all the way to the gunwale

Is the casting deck adding support to the hull? Next gusset can go on top the casting deck as the strap isn't doing a lot.

Or you can again go from floor to top of gunwale.

[jwmiller33]

Thanks for the input Frank. I guess I am not following all of what your saying. How would I make gussets out of plywood? How would they double as rod storage? How do I mount alum angle to the boat? Would I need a rivet gun?

I don't think the vibration is coming from the removal of the middle bench. It didn't use to vibrate like that with my old motor. Got a different motor a year or so back and thats when it started. Both motors were same size (35hp)

[DTro]

I bet a new motor would solve all your vibration issues. LOL

[jwmiller33]

i think your right dtro! i have been dreaming about a new[er] 4 stroke 40hp for a long time now... some day... as for now, good old Walter Johnson is going to have to make due