Stupid question

I am in the process of purchasing a steel sailboat. During the survey, four of six zincs were gone. I had some zinc plates drilled and installed because the yard did not have the right kind in inventory.

The bolts used to secure the zincs were shot too. A trip to a local shop gave me the option of zinc covered steel bolts or stainless steel. The yard recommend SS; I purchase the zinc covered steel bolts.

Did I do wrong?

The boat must come out for a paint job in a few months, so I can correct the situation soon, i.e., proper tear drop zincs and change the bolts if required.

TIA.

P.S. The ultrasound found NO hull material missing. Boat is five years old.

 

The stainless (I think) is more noble than regular bolts. Both types are more noble than the zincs. I can't see where it would make much difference other than to the yard for selling more expensive items. Maybe speaking with some of the local commercial fishermen running steel boats would be in order.

 

For the zinc's to work, they need to be in good electrical contact with the hull. How are they bolted on? Best practice is to shoot a CD stud (steel or CRES) after painting the hull, touch up the paint, bolt on zinc with a bedding of zinc paste around the bolt/washer/nut. Replace the studs as needed. As for myself, I wouldn't recommend SS bolts on a zinc. There are electrical potential , crevice corrosion, and hydrogen embrittlement issues depending on what SS class is selected.

 

There is a metal plate welded to the keel and hull to accept bolted on zincs. The yard ground flat the steel plate so the zincs would have a good connection to the hull.

I will see about getting the the zinc paste. I didn't use SS because of the crevice corrosion issue and electrical potential. Glad I was thinking correctly.

This metal boat stuff is all new to me.

 

Check out the internet for some books on steel boatbuilding. By reading 3-4 different ones you'll get several views which youy can pick & choose from. I've personally accumulated 4 that I can think of; one by Colvin, Bruce Roberts, "Steel Away" by Moir & Smith (I think), and Kringil (SP?) a small hard back obtained from Robert's. There are many others I have been made aware of through the net.

Though you already have a boat, the knowledge obtainable through good books will prove very useable in living with a steel boat in the longterm.

TGoz

 

Book: Metal Corrosion in Boats

I have this book in my lib, it's very clear and informative, not specifically for steel boats .


http://www.amazon.co.uk/gp/product/...ef=sr_1_1/026-1738061-3794037?ie=UTF8&s=books

 

I would never drill a hole through a hull umless I really had to. My steel yacht that I used to have had bolts of similar metal as the hull. These were welded on at there heads. the anodes were then bolted to them.

 

Thanks. Funny thing, have several books on metal boats but they have been in storage in Alaska for the past five years. Ironically, today I leave for Alaska where part of the activities included packaging about 30 sailing books and shipping them back here.

BTY, I have another book on metal corrosion in boats, and it's fantastic. I just haven't had time to fully digest it. It's new. I'll post the name and author in a couple weeks when I get back.

Thanks to all for the help.

 

Hiracer,

Where are you heading to in AK? I got to spend a couple of summers up in SE AK, one in Ketchikan & one on the norht end of Prince of Wales Is. around Port Protection.

TGoz

 

Just got back. Visited in-laws in Anchorage.

Check out my old boat in Seward. Sure do miss the sailing and cruising there.

Just purchased yesterday a metal sailboat with intended use to cruise SE Alaska once we retire (in about a 100 years from now).

Going to buy a chart of San Juans Island now. Later.

 

Hiracer
Read my attached file. Feel free to ask any questions

Cheers
Mike