Safty Harness anchorage

[mikenda - delete]

I am planning on installing an anchorage point for a safety harness in the cockpit of my Moody 346. Advice please on the fitting of backing plate’s etc.

 

[LORDNELSON]

You can obtain either a hinged type anchorage which is attached with two bolts or use a "U" bolt. Personally I have always used U bolts because I do not trust the hinge joint and do not like the use of countersunk bolts for attaching the base of the hinge to the cockpit side. If you use a U bolt the minimum size would, in my opinion, be an M6. It is likely that you will be attaching it through a single layer of GRP and to prevent a shock loading pulling the U bolt anchorage through the GRP you do indeed need a backing plate. I use a circular or oval hardwood disc at least 12 mm thick and 75 mm in diameter with a smaller stainless steel plate of the same geometry behind the wooden disc; the U bolt is taken through holes drilled through the grp, the wood and the stainless steel plate and then bolted on using the rectangular backing washer supplied with most good U bolts. Ignore any claims by manufacturers that their U bolt has special seals to prevent water leakage and ensure that the u bolt is fitted using plenty of waterproofing medium (sikaflex or similar setting but non-hardening filler). It is simpler if you are fitting the U bolt through several layers of grp/wood because you can reduce/omit the backing disc. Hope this helps.

 

[rogerroger]

I've just done this with a U bolt. I used a 10 inch strip of 13mm ply left over from some interior construction for the back plate. Seems sturdy enough to me, in fact the job was so easy I'll probably do another two.

Roger Holden
www.first-magnitude.co.uk

 

[Trevor_swfyc]

The anchor point should come with a backing plate, I would not think that you required more than this as the moody lay up will be thick enough to take the load.
Take a look at the back stay backing plate and think of the load this is under.
Trevor

 

[billmacfarlane]

I used U bolts , with plywood backing plates , about 3" square , and penny washers , the whole thing bedded in with Sikaflex.

 

[claymore]

Agree with Bill and used my own backing plates just to spread the load. I also used nyloc nuts onto the U bolts. Think about where you are putting them as if you don't they will snag on spinny or genny sheets or be right where your foot goes when you are coming alongside or something irritating like that
regards
John S

What care we - tho' white the Minch is,
What care we boys, for wind or weather?

 

[dickh]

Yes, use U bolts as posted earlier. I reckon M8 size with a large backing plate of plywood with mastic. Don't forget that if your safety lines have 'carabiner' type hooks that they are liable to capsize and release under certain circumstances - you must fit ss rings on the U bolt and clip onto the ring. U bolts are ferfectly OK with Gibb, Wichard and similar clips that have a dual locking action. Make sure you fit sufficient U bolts so that you are not all clipped at the same point. I have 3 in my cockpit, port & stbd at the forward end and one at the rear.

 

[AndrewB]

Desert Island Discs? (nm)

nm

 

[mikenda - delete]

Thanks to all contributors