Boat shakes.

Alex from GA · Jan 8, 2021

I have an '87 Grumman Renegade bass boat and it shakes in anything but smooth water. I put a tight wood block between the hull and the console which made it shake less. It shakes so much it's hard to see the locator on the dash. I screwed the console to the floor last year but that didn't help. It seems that the floor/deck itself is shaking. Is there anything I can do to to calm it down besides slow way down? If I go 12 or 13 mph it isn't too bad.

I've never had a tin boat until this one. BTW I have a 9" Humminbird on the console.

MrGiggles · Jan 9, 2021

None of my tin boats have ever shaken on plane.

Is the vibration from hitting chop, or from the outboard?

CedarRiverScooter · Jan 9, 2021

Since he said it is OK on smooth water, I bet it is just the chop hitting the flat bottom. This is the nature of a flat bottom boat. If it isn't going to be acceptable, you are best off to trade for a semi V. No way to fix it, other than to reinforce your console mounting.

RaisedByWolves · Jan 9, 2021

Yea a flat bottom tinny will take a pounding on anything other than glass smooth water.

Youre trading comfort for speed essentially.

Alex from GA · Jan 9, 2021

Thanks guys. I payed close attention to it yesterday and it seems like the floor is shaking too. It's not a complete flat bottom it has some deadrise, probably less than 5*.

MrGiggles · Jan 9, 2021

Alex from GA said:
Thanks guys. I payed close attention to it yesterday and it seems like the floor is shaking too. It's not a complete flat bottom it has some deadrise, probably less than 5*.

A ram style mount for the graph would probably help with that problem. They're quite a bit more rigid, might help take the bounce out.

maintenanceguy · Jan 10, 2021

I'm not sure that we understand what "Shakes" means. Is the boat porpoising where the front end rises and falls? Is the boat vibrating as it skips along on the water? Is the stuff inside the boat (console, floor) rattling? Is the motor surging and the boat speeding up and slowing down?

Alex from GA · Jan 10, 2021

The rattling is the best symptom. Engine runs good, new prop, only porpoises when trimmed up too far. The Ram mount is probably what I'll get.

LDUBS · Jan 10, 2021

My boat, which is a semi V, has a pretty rough ride if I go fast in even small chop. But I'm OK reading the FF. I agree upgrading the mount might be a good idea. I hope it works for you.