Engine Beds - What Wood?

Major_Clanger said:
I've buckled and have decided to put an engine back in to my boat. I can use the existing beds with some modification and plan to use 18mm marine ply glued/screwed together and encapsulated in Wests.

Is marine ply a good choice or should I be using a hardwood?
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I wouldn't encapsulate it in epoxy, a) because there's no need, and b) because the timber might rot if moisture gets in.

I believe oak is the traditionally used timber for engine bearers.
 
Major_Clanger said:
I've buckled and have decided to put an engine back in to my boat. I can use the existing beds with some modification and plan to use 18mm marine ply glued/screwed together and encapsulated in Wests.

Is marine ply a good choice or should I be using a hardwood?
Click to expand...

It really depends on how you are going to fit the engine mounts to the timber. If you are going to bolt through the timber then Oak has superior crush strength than plywood. How do you propose to fix the ply to the existing beds?

Www.solocoastalsailing.co.uk
 
When I got my Centaur converted from Volvo to Nanni my engineer bolted on two approx 75 by 50 mm. Iroko longitudinal bearers to the original grp . A few coats of Danboline and AOK.
 
From an engineering point of view, it should be a hardwood. Ash and beech are mechanically OK, but they both rot at the drop of a hat. Oak is just about ideal, but it may warp a little if not seasoned. Iroko is also good, and won't warp, but it's not quite as strong or crush resistant. Teak would be wildly over the top.
 
Ply would be fine, but no need to encapsulate, although coating with epoxy particularly the end grain would be a good idea. I used ply to raise my beds. Glued and screwed to the original oak beds then engine mounts attached using stainless M10 hex head lag bolts.This method allows you to get the engine lined up properly then drill the holes in the beds for the mount screws. Takes the guesswork out of alignment.
 
Usual way for FVs I come across is foam with a steel plate, drilled and tapped, on top and grp over. I never liked that, and did it with multiple, 3 or 4 x 18mm WBP ply, with transverse stiffeners, GRP overall, then angle iron bolted on the inside. Means you can get to engine feet bolt nuts, have a good steel on steel mounting, and move the arrangement should you change engines. 80hp Ford sitting on it, still fine after 35 years.
 
Thanks for the replies chaps.

The existing beds (which will need to be cut down and then added to in a horizontal plane) are encapsulated hardwood. The engine mounts will be through-bolted to the new wood and I'll make the nyloc nuts captive if possible. I won't know for certain though until I've finished the engine jig.

I like the idea of oak, but it's not easy getting good stuff nowadays and so I'll probably use decent ply (with the ends treated - thanks!). The whole unit only weights 70kgs so not too much of a pain to pull out in the future should I need to change the beds.
 
Oak sleepers are readily available - we use them for small landscape structures and they don't seem 'bad' though possibly not as good as open grown English oak.

They do dissolve steel fittings though, as they can be quite green.
 
I replaced the engine on my previous boat and modified the original bearers with a couple of bits of oak I found on ebay.
I had to plane them down to the reqired size but it worked pefectly.
 
On my Co26 I removed the original Vire bearers which were too high and epoxied in two 3" x 3" iroko bearers about 3ft long tapered to almost nothing at the aft end. These have lasted over 25 years but I recently added 50mm x 8mm tapped A4 SS strips to the top of the bearers which gives a better spread of loading for the rather lively 1GM which rocks around at tickover.
 
Major_Clanger said:
I like the idea of oak, but it's not easy getting good stuff nowadays and so I'll probably use decent ply (with the ends treated - thanks!). The whole unit only weights 70kgs so not too much of a pain to pull out in the future should I need to change the beds.
Click to expand...

Oak isn't difficult really: Seasoned - https://www.gards.co.uk/product-range/oak-hardwood, near Colchester. I rebuild the infrastructure for TG's cockpit using oak from them (and then for some decorative stuff on the house extension). For green oak I went to: Tutton Timber - http://tuttontimber.co.uk/about_us.html They cut me some green oak 2 metres x 30mm x 30mm at £2 a stave for steaming ribs. It was just sawn but it was easy to plane up. Gards will be fully planed. Gards is high quality timber, Tutton is for more rustic but I asked for clear and got it.
 
andsarkit said:
On my Co26 I removed the original Vire bearers which were too high and epoxied in two 3" x 3" iroko bearers about 3ft long tapered to almost nothing at the aft end. These have lasted over 25 years but I recently added 50mm x 8mm tapped A4 SS strips to the top of the bearers which gives a better spread of loading for the rather lively 1GM which rocks around at tickover.
Click to expand...

Would really appreciate a photo next time you're at the boat please as mine is also a Co26 with beds for a Vire.

tillergirl said:
Oak isn't difficult really: Seasoned - https://www.gards.co.uk/product-range/oak-hardwood, near Colchester. I rebuild the infrastructure for TG's cockpit using oak from them (and then for some decorative stuff on the house extension). For green oak I went to: Tutton Timber - http://tuttontimber.co.uk/about_us.html They cut me some green oak 2 metres x 30mm x 30mm at £2 a stave for steaming ribs. It was just sawn but it was easy to plane up. Gards will be fully planed. Gards is high quality timber, Tutton is for more rustic but I asked for clear and got it.
Click to expand...

That's a useful recommendation, thanks very much. :)
 
Major_Clanger said:
The existing beds (which will need to be cut down and then added to in a horizontal plane) are encapsulated hardwood. The engine mounts will be through-bolted to the new wood and I'll make the nyloc nuts captive if possible. I won't know for certain though until I've finished the engine jig.

I like the idea of oak, but it's not easy getting good stuff nowadays and so I'll probably use decent ply (with the ends treated - thanks!).
Click to expand...

Wouldn't some metal structure be better suited for this task, rather than wood?
I used rectangular stainless steel tubing, found at the scrapyard for not a lot of money, when I needed to raise the beds as a new engine was installed.
motortass.jpg
 
LittleSister said:
The other potential way too look at it (depending on the geometry, etc.) is getting brackets made up to match the engine to the existing beds.
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If the beds were suitable I'd do that but not a chance sadly. Vire engines are tiny and the beds are much too small and close together.

BabaYaga said:
Wouldn't some metal structure be better suited for this task, rather than wood?
I used rectangular stainless steel tubing, found at the scrapyard for not a lot of money, when I needed to raise the beds as a new engine was installed.
motortass.jpg
Click to expand...

Sound idea but I want to bond one face of the new bed to the hull, and so wood is better for that.
 
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