Mast Corrosion at Boom Attachment - $$$?

[Scaramanga F25]

To address your concern you could replace the two stainless fittings on
the mast with a custom one piece fitting a little larger.
Then clean,paint and isolate.

[skipmac]

Originally Posted by meirriba

Everything will become clear once you remove the screws and see the mast behind the gooseneck.

Yes but removing the screws I am guessing will not be easy. I'm currently working on my 30 year old mast and I'm only getting about 1/3-1/2 of the screws out in one piece. Even after soaking with penetrating oil, heating and tapping.

[seasick]

Those I36s are fun boats. I would suggest this small bit of corrosion is going to be the least of your concerns. Look very closely at the mast step for corrosion and the keel bolts.

For far more information on areas of concern, spend several hours on the
Islander 36 Owners Association website: Islander 36 Association, sailing, racing, cruising and maintaining sailboats

[seasick]

Oops here is a more specific link:

http://islander36.org/maintain4b.html

[jeepbluetj]

I fixed alot of my boom that looked like that. Just sanded and repainted (alodine, chromate, etc...)

What's the consensus about using riv-nuts instead of re-tapping a larger hole in this case? I hypothesize tat even if the SS bolts were not tefgeled and the AL corroded again, the riv-nut will corrode instead of the mast/boom.

A thin sheet of polyethylene (a report cover or something, i've even used packing tape) can also be used between a SS plate and the AL spar.

[Cheechako]

It's very common due to mix of metals. My pro painted mast started that again after one year cruising. It was acid washed and chromate primed etc. I've often thought that stripping the mast from the deck up maybe 6 ft would be better.... at least cosmetically. If the fittings have screws be prepared to break them all trying to get them out... unless lanolin or other material was used when they were installed.

[bsurvey]

that mast is a tree, the section is really thick in comparison to other vessel. the mast is obviously painted and the condition in the photo is not unusual.., scrape the blisters away and see if its a pit or whether its just some corrosion from poor paint prep. they may not have taken off the gooseneck before they painted it last time.


if it turns to be anything significant, the area can be doubled over with another piece of aluminum extrusion and mechanically fastened to the mast. ie tapped and bolted.
if this is the only thing wrong with the boat then you are lucky.


usually the floor timbers at the keel bolts are all delaminated and the bulkheads delaminated. the stem fitting may also be pulling itself through the stem frp.


one of the weak points of this boat regarding the rigging is the port aft lower shroud. its is only held to with a knee frame at the deck shear. rub you hand over the deck and see if there is a lump

[The Atonement]

Originally Posted by seasick

Those I36s are fun boats. I would suggest this small bit of corrosion is going to be the least of your concerns. Look very closely at the mast step for corrosion and the keel bolts.

Luckily the mast was unstepped by the current owner a couple of years ago. It did have the "traditional" problems at the base. about 2 inches was amputated and then rebedded in a 2" lift so the net loss was zero.

During my inspection I saw a small area of potential rot under one of the berths hiding behind a tank which will need a bit more exploration, and there is also a spreader that I was able to see whilst zoomed way in with my camera that appears to have experienced a bit of trauma.

Once we get it hauled out I can inspect the bottom but by then the paid survey will be in progress. My photos of the top edge of the rudder appear a bit suspect, though the bottom job is only supposed to be about 4 years old. (We'll see.)

[The Atonement]

Here's the rudder top. Hopefully not an example of the entire hull condition.

Also one spar was deflected downward slightly. After zooming in with the camera I could see a small crack in the notch. Never would have noticed with naked eye.

[The Atonement]

Originally Posted by seasick

Oops here is a more specific link:

Islander 36 Maintenance

Spent lots of time digging around that site already. Love the cockpit bench under "Owners Projects"

I could see it making a major improvement in visibility while seated at the helm.

[JPA Cate]

The Atonement:

Other places you want to get a good look at include the spreader attachments.

FWIW, we often use old inner tubes for a galvanic isolator, like between the gooseneck attachment and the mast. But, you really do want to see what it looks like underneath. If it's good, you're good to go, but if severely pitted, then, maybe not.

Ann

[svTOTEM]

A note on TefGel - great stuff, but not the best choice for isolating flat surface areas. I've found TefGel to be effective for 4 to 5 years on threads. For flat surfaces a thin layer of weather resistant, non-conductive plastic such as UHMWPE (some flexible cutting boards for example) or solid chemical layer such as Duralac will last much longer.

[transmitterdan]

Most plastic 1 gallon milk jugs in the US are a good source of isolating material. Flat pieces are usually easy to excise from the jug.

[hodgmo]

Info specific to Islander36 goosenecks available here:

Islander 36 Booms