Packing for under engine bearers?

[dgadee]

I installed new engine bearers, but there's a goodly bit of movement under power due to the rear ones being set quite high up the threaded upright shaft. I think I need to put packing under these to reduce their movement - maybe 30mm in depth. What should I use? I would prefer not to use hardwood.

 

[Tranona]

Assume you mean that the beds are now too low leading to the engine being towards the top of the adjustment on the mounts. If this is the case then you need to raise the beds and hardwood is an appropriate material to use. Just putting a packer under the mount is not a good idea. The bed should be continuous so that both mounts are on the same bed. Bond a piece of hardwood onto the existing bed with fastenings so that it is firmly attached and then attach the mounts with fastenings that go through new piece into the bed underneath. The thickness of the new piece should be such that the engine sits at the mid point of adjustment on the mounts.

 

[GrahamM376]

As with many boats, our engine mounts are on spacers made from solid alloy block, drilled to suit. No movement, no problems after 28 years.

 

[PCUK]

You could also use epoxy coated steel as a cheaper alternative but marine alloy will certainly offer the best solution.

 

[chrishelen]

I used a bit of plastic chopping board on one of my boats. Never had a problem over 6000 hrs.

 

[dgadee]

Thanks all. I can't see why packing spacers won't work - they are held in compression by the bearer bolts and essentially become part of the boat to which the bearer is attached. I quite fancy industrial plastic bar of some sort - will have a look at what is available.

 

[LittleSister]

Thanks all. I can't see why packing spacers won't work - they are held in compression by the bearer bolts and essentially become part of the boat to which the bearer is attached.

Depends how wide your spacers are, and how well fixed to the bearers. Packing spacers may not work well for the same reason the bolts on the mountings don't and move about: the load is not just vertical but backwards/forwards and side to side too. If the spacers are too tall and narrow they are likely to move about. So the issue is getting a broad base, well fixed to the bearers, that the mounts can be fixed to or through. Whether you call that a spacer or a raised bed doesn't matter.

 

[RobbieH]

As with many boats, our engine mounts are on spacers made from solid alloy block, drilled to suit. No movement, no problems after 28 years.

+1

 

[lw395]

Depends how wide your spacers are, and how well fixed to the bearers. Packing spacers may not work well for the same reason the bolts on the mountings don't and move about: the load is not just vertical but backwards/forwards and side to side too. If the spacers are too tall and narrow they are likely to move about. So the issue is getting a broad base, well fixed to the bearers, that the mounts can be fixed to or through. Whether you call that a spacer or a raised bed doesn't matter.

+1.
It's normally easy to make the spacer long enough to be stable fore and aft, side to side can be awkward on some boats.
There is side loading from propshaft torque and vibration.