26S Filling with Water and vanishing Bolts

[martyr]

STAINLESS or BRONZE (though a stainless pivot) below the waterline?

When I rescued my new to me 26S from the Oregon coast it was slowly sinking ass first into the pacific.
The below the waterline rudder pivot bracket was leaking badly and the Laz was full of seawater to the top of the starter battery.

The rear bulkhead was intact but slowly leaking into the forward section of the boat.

Of the four STAINLESS bolts holding the STAINLESS rudder bracket to the back of the boat.

1 was missing the entire bolt head.... given to Neptune I suppose
1 split in half when removing
1 was half dissolved but survived removal
1 pristine

Help!

Should I replace these bolts with Bronze, but IGNORE the dis-similar metals (rudder bracket is stainless) advice people warn about.
OR just replace the bolts with new stainless ones and check them every few years.

Ps. I did drill out the leaky bolt holes till I found good wood and will fill n drill with epoxy.

Next will be removing the scum line from the inside of my boat....

[cruiser]

I found the bolts in mine to be pretty much in the same condition as yours. Just replaced them with new stainless steel ones. The originals where 1/4" x 1 1/2" but they stuck out a bit inside the lazarette so I replaced them with 1/4" x 1 1/4" 316 stainless steel. I think using 316 is important here because they are sitting right next to the waterline.

I do think they need to be checked every 4-8 years depending on how much you use the boat. The transom is a good 1/2" thick where that rudder post support bracket fits on so it can take a pretty good load providing the glass itself is in good condition. That was a good idea to clean out and plug the bolt holes with epoxy.

I wanted to use butyl tape under my support bracket and bolts but found it too difficult to line up the post flange and bolts without distorting the butyl, so I just used tubed marine sealant underneath the bracket and bolt heads - a bit fiddly but do-able. I countersunk the bolt holes just to make sure there was ample sealant in around the bolts and a bit of room for fleaxing in the sealant (see photo).

[mastreb]

Do not ignore the dissimilar metal advice. Bronze attacks stainless aggressively through galvanic corrosion and seawater is a near perfect electrolyte--they don't even need to be in contact, they can be inches away and still corrode through a seawater conduction. You'll get much better lifetime out of using all 316 stainless. While you could put a lot of sacrificial zincs on, it's just easier to use the same metal everywhere.

Easy way to tell what your corrosion life will be: put a bronze fitting and a stainless fitting in a clear glass of seawater and put it on your kitchen window sill. As it corrodes, keep in mind that the exact same thing is happening to the fittings on your boat.

[cruiser]

The sealant I used on mine was a Fixtech product MSP15 http://www.fixtech.com.au/process/catal ... goryId=571 - I tend to use it in situations where I cannot use butyl tape. Fixtech is an Australian company so their products may not be available over your way. I think Sikaflex 219 http://usa.sika.com/en/solutions_produc ... 01101.html would probably be a good choice and should be available OK. Stay away from 3M 5200 as it has far too high an adhesive strength and that may cause problems when you go to re-do the fitting some time in the future.