Do I need to bolt or can I sikaflex and screw?

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Oscarpop

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Am planning the installation of our wind generator which has a main pole and two supporting struts which attach half way up the 9ft pole .

The main pole will be bolted through the deck with some hefty backing washers as well as sikaflex.

My question relates to how to attach the supporting struts to the deck. One will definitely be bolted as its straightforward. However the other will be a total bugger to get to the back to attach washers and nuts.

Can I use screws and sikaflex, or,is this not strong enough?

As I remember, a rigger once added a clutch to the deck without bolting it , but again that may not have been best practice.

Thanks
 
The max/peak/100 year loads will be very difficult to calculate. It's fair to presume that something unforeseen will impact the structure, and you'll be blurry glad you made it 'squaddie proof'.

You indicate that backing washers and nuts will be seriously difficult. Have you considered 'potting' small bolts into the deck layup, using thickened epoxy ? The Gougeon brothers' excellent tome describe this, and more detail can be had from the UK distributors of West System epoxy products. Works...

Could be the answer to a maiden's prayer..... :D
 
Winds are probably not the issue. Consider hitting the end of the pole with a sledge hammer every ten seconds. That's what the supports will experience while you're at sea. if you can't fit bolts, try extra supports or using wire supports to an area you can get to. Alternatively, I wonder if you can get something like a butterfly fixing in stainless.

Stronger the better IMO.
 
Epoxy potting for windmill mounts?

oldbilbo said:
The max/peak/100 year loads will be very difficult to calculate. It's fair to presume that something unforeseen will impact the structure, and you'll be blurry glad you made it 'squaddie proof'.

You indicate that backing washers and nuts will be seriously difficult. Have you considered 'potting' small bolts into the deck layup, using thickened epoxy ? The Gougeon brothers' excellent tome describe this, and more detail can be had from the UK distributors of West System epoxy products. Works...

Could be the answer to a maiden's prayer..... :D
Click to expand...

I used this for fixing camcleat backing pads on the coachroof, worked like a charm.

BUT - the load on my clamcleats bolts is in shear. The load on the supports for the windmill will be alternately in compression and tension. That may maked short work of the epoxy/steel bond. If you are going to do it use a glueing epoxy made for the purpose which remains slightly flexible.

I would not recommend it having had the interesting experience of hanging off the stern of my Arpege in the middle (really the middle, somewhere well offshore in S. Utsire) of the North Sea. I had to drill a couple of 4mm holes (with a wheelbrace, no battery powered drill on board) in the upstand that housed the pole that my windmill was mounted on. This was so I could pass a bolt through. The base was almost jumping out of its (4 inch long) socket as we bashed to windward in a F6. That was an interesting couple of hours (hove to). The thought of the windmill crashing into the cockpit whilst spinning at F6 speeds was not really very palatable. So from my experience I would say do it right with bolts and backing plates.

The other thing you might be able to do is mount the offending brace onto the pushpit and transfer the loads via the pushpit. In fact that is what I have done with my windmill for the braces (not the main pole), it works really well - but then my Arpege has a fairly sturdy pushpit which is itself mounted with many bots and backing plates.

Can send some photos if you are interested ...
 
It's very hard to say definitively.
If the deck is sandwich, screws into epoxy bridging the sandwich could be made pretty strong.
Probably possible to make it as strong as a small bolt with a backing washer.
It's hard to guess the loads without seeing the whole installation.

There comes a point where strengthening the fixing just means that in a damage situation, the damage gets transfered from the fixing to the panel its fixed to.

OTOH, a generator mast is reasonably likely to get used as a handhold, so should be able to take a fat bloke falling against it.
I would be thinking in terms of bracing it to naturally strong bits of the boat, eg toe rail, or getting the loads into shear forces in the panel.
 
I suggest you talk to your local fixings specialist. There are many stainless steel blind fixings available. (Google 'the nut and bolt shop' or 'Namrick', if they still exist)

If the area you intend fixing to is cored, then suggest something like boring an oversize hole and initially filling it with an epoxy filler, then when set rebore smaller dia. and use a blind fixing.
 
wooslehunter said:
Winds are probably not the issue. Consider hitting the end of the pole with a sledge hammer every ten seconds. That's what the supports will experience while you're at sea. if you can't fit bolts, try extra supports or using wire supports to an area you can get to. Alternatively, I wonder if you can get something like a butterfly fixing in stainless.

Stronger the better IMO.
Click to expand...

+1

For instance, an Aerogen 4 weighs 8.5 kgs (excluding pole) and should be up an 8ft pole to achieve blade head clearance. When the boat starts rolling, that's a hell of a pull on the fixing points when the load changes direction. My physics is c*ap but no doubt someone can supply the figures.
 
I think the loads transferred down the pole from a wind generator are prone to exaggeration.

My Aerogen is on a pole that is just clamped to the pushpit with two "U" bolts. It's been there for many years even through severe winter gales keeping my batteries nicely topped up.

The stresses placed on the pushpit have never been a problem.
 
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