O'day 34 backstay backing plate

njlarry · Apr 9, 2017

Thanks for posting. I never realized that the backing plate was wood, I'll have to check mine. From the pictures it looks like the backing plate was still structurally sound. Where does the ground wire terminate?

jibes138 · Apr 11, 2017

I found that teak in rough shape too a couple years ago. I used plywood to replace it and also went with butyl. G10 would be a good material for this.

rajhnsn · Apr 11, 2017

I'm definitely checking mine. I didn't know it was wood either. Pretty much a critical piece. Heading down this week to prep for the big splash.

jibes138 · Apr 12, 2017

It's a pain to get at. Two people will improve the process. I was able to jury rig a wrench to hold the bolt heads while I removed the nuts but having some one there to help unscrew the bolts and reinstall them is a plus.

eherlihy · Apr 12, 2017

If I recall correctly, the backing plate for the backstay on my 1987 O'day 35 is stainless.

I've been in this location, and it is not pleasant. The easiest way to get in here is to remove the liner from the spare propane locker (starboard), To remove that involves removing the engine compartment access door and the rear panel from the rear quarterberth.

That wire is a bonding wire. It runs from one of the bolts that secure the backstay through the middle of the bilge compartment and eventually bolts onto one of the keel bolts. There are other ones that comes from; the mast, the port upper shroud, the starboard upper shroud, and the forestay. Here is a picture of where they all come together under the base of the mast.

Along the route that each of these wires takes, there are splices which connect to the engine, and each of the bronze through hulls.

I have removed these connections on my boat, as I do not want to risk galvanic corrosion of my through hulls.

Captmayhem · Apr 12, 2017

love the common sense of having the plugs tied ready to the handles!

njlarry · Apr 12, 2017

I agree it is best to remove the wire from the thru hulls. When I got my boat the holding tank thru hull was the only one not connected and it was also the only that didn't need to be replaced.

rajhnsn · Apr 13, 2017

Your bilge under the mast is much cleaner than mine. Did you document your process for replacing the intake seacock?

eherlihy · Apr 13, 2017

Note that if you remove the connection from the through hull, you are increasing the probability of damage to the vessel in the event of a lightning strike. On the other hand, one could argue that you are decreasing the likelihood of a lightning strike. An absolute best-practice on lightning protection has, IMHO, not yet been determined.

The process for replacing the seacock is well documented at Maine Sail's site, and I used his method with 3/8" G-10 backing plates. Note that the 90º fitting should be INWARD of the seacock, and if you have a "scoop with grate" through hull it should be removed, as these make great nurseries for mussels.

A client of mine has a "scoop with grate" seacock which connects to a 90º fitting, which then connects to the seacock on his O'35. He has asked me to straighten this out for him while his boat is on the hard. Because his yard does not allow me to work on his vessel, I have had to tell him to do it through the yard (and I'm pretty sure that they will screw it up).

jibes138 · Apr 13, 2017

I removed that strainer and ball valve on mine also much like the picture above. Note the strainer ID is 1/2 inch and IIRC the raw water pump inlet is larger so the strainer limits the cooling water flow, add a few critters growing in there and a few layers of paint in the slits and you have a potential for overheating.

eherlihy · Apr 14, 2017

Back on topic;
I went to the boat today, and I stand corrected. The backing plate on my '87 O'day 35 IS teak;

jibes138 · Apr 15, 2017

I used plywood to replace it but if I had the material on hand I'd go with g10. Any metal can corrode (unless you use gold or platinum) and wood can rot. G10 you will never worry again.

njlarry · Apr 15, 2017

What are those hoses and is that a thru deck fitting?

eherlihy · Apr 15, 2017

njlarry said:
What are those hoses and is that a thru deck fitting?

The hoses run to my Rule 2000 Gold electric bilge pump, which discharges out the transom. That is not a through deck fitting, it is an anti-siphon loop.

eherlihy · Apr 15, 2017

jibes138 said:
I used plywood to replace it but if I had the material on hand I'd go with g10. Any metal can corrode (unless you use gold or platinum) and wood can rot. G10 you will never worry again.

THANK YOU FOR THAT!!! I have a piece of 3/8" G10, that will do PERFECTLY!