I/O hull flex question?

[jaknight]

I have a sunbird bowrider with a volvo aq125a / 270 setup. When I am out on the water I notice quite a bit of movement in the motor. It seems like a lot but its really the front of the motor moving up and down only maybe 2-3 inches. I found tons of threads about outboards saying they should not move at all. But this is a 4 cylinder inboard hanging out from the hull with no other support. The gelcoat is fine and with all my weight on the outdrive I can not really see any flexing in the hull itself. It looks maybe more like the mount is shifting.

How much flex is too much with this thing? Has anyone ever added a front motor mount to remove some of the stress from the hull?

 

[Grandad]

Welcome to Iboats jacnight! I'm not that familiar with Volvo mounts, but that much play sounds excessive to me. Is this an older boat with suspected rotting transom support? - Grandad

 

[jaknight]

I don't see feel or hear anything that suggests. I pulled the pilot off and the screws were clean inside the wood. Non protected screws that were rusted outside. No signs of water getting in the boat. I was docked for three days and the bilge was dry.

 

[jaknight]

Thanks by the way. This forum has already answered tons of questions I have had.

 

[Scott Danforth]

There should be no play. the motor is bolted to the transom and to the mounts on the stringers. if the motor is moving, something is not right.

 

[garbageguy]

...It seems like a lot but its really the front of the motor moving up and down only maybe 2-3 inches...But this is a 4 cylinder inboard hanging out from the hull with no other support./QUOTE]

That's too much movement. I'm not familiar with your boat, but, no other support? No motor mounts?

 

[Watermann]

The older model of VP has no front motor mount like a Mecruiser does, they hang off the transom only in mid-air. The way they trim is by a pump on the back of the motor that tilts the entire motor up and down. It could be that the pump is not keeping pressure against the motor and allowing it to go through it's range of motion.

I suggest you have a mod move this thread to the VP section where guys who really know what their talking about can confirm what I told you. I only know a little about them as I helped a buddy pull his motor and VP assembly from an 80's Bayliner.

 

[jaknight]

You are partially correct. The motor hangs from the transom with no other support. There are no other mounts and there is no support at the top of the transom. If I put my 200 lbs on the front of the motor it drops maybe 1/2 an inch. 2-3 inches may have been exaggerated. The motor itself does not tilt or move. Its very simular to a mercruser except there are no mounts.

 

[jaknight]

If a mod could please move this to the Volvo penta forum that would be great. Thanks.