Replacing Crossmembers

ahicks

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I wouldn't, for the simple reason it may end up trapping sea water that could possibly do more damage than if left untreated?
 

tablerockboater

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OK.

I'm just thinking that if the original stringers had been treated with something, they may still be OK.
 

tablerockboater

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Here's where I'm at. I've acquired stringers and a transom (not necessarily the right size) and need to get the stringers in place and fasten them.
 

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tablerockboater

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I was delayed by surgery, but our last week in Florida for the season I was able to get all the new-ish stringers and transom installed. The boat never left the driveway so hasn't been back in the water yet.

Any ideas on anything I could put on the stringers and transom to protect them from saltwater corrosion?

Thanks.
 

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tablerockboater

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I found this:

"Above the waterline aluminum does even better. When continuously exposed to oxygen, it develops a film of aluminum oxide so dense and well bonded to the metal that it prevents further corrosion. That’s why many commercial and military craft leave aluminum bare from the waterline up: There’s no need for protective paints, cosmetics aside. As you can see, building an aluminum boat for salt water takes thought. The right alloys must be used, welding must be done just right, and parts must be carefully assembled."

I guess that means they will form their own protective coating, maybe already have.

But, the same article mentions that aluminum comes apart rapidly in the presence of other metals. I suppose that means the bolts I used to fasten everything. Maybe I should spray something on them where they are touching the stringers and transoms. Maybe it was the bolts holding those items on that caused the corrosion.
 
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MH Hawker

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sharkhide is used on the toons so it should do fine on a cross member
 

jbcurt00

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If used in salt, I hope all the fasteners you used were stainless steel. If not, no idea what you could put on them to protect against dissimilar metals corrosion (brain fart, its galvonic corrosion, correct?)

It'd eventually occur in fresh water too, the salt just speeds it up..
 

tablerockboater

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Thanks both.

I'll try sharkhide. I did not think about the toons being coated, which they are below water level.

&, I mentioned the bolts (fasteners) . . . I stumbled onto that after the job was done.

dang.

Oh well, the originals lasted almost 20 years, and I probably won't.
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I found this on Sharkhide's website . . . it's a little disappointing:

In the marine industry, SHARKHIDE is used primarily on aluminum hulls such as Pontoon boats, Houseboat, and Fishing boats. In most instances, a couple of good coats can last many years. It's not uncommon to see three to five years of protection.
 
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tablerockboater

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How about this stuff:

m-and-l-marine-tbrite-clear-protection-coat-12oz
 
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tablerockboater

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I'm asking this again. It's M&L Marine Toon-Brite Clear Protection Coat 12oz PA1000 spray can.

The product description sound like exactly what I need to protect the stringers.

I'll wait to order any, hoping for some replies.
 

tablerockboater

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Now that I've studied galvanic corrosion in salt water, do you think that's what happened to the stringers of my pontoon?

There are anodes, long ago sacrificed, on the toons. Should I replace them?

I found this on a pontoon manufacturer's website:

Zinc anodes should be installed on your aluminum pontoons at the dealership, these should be installed below water level on the transducer brackets, your boat engine should already be equipped with them. Inspect the zinc anodes frequently for deterioration. A sacrificial anode will deteriorate before the metal it protects. If the zinc anode erodes 50% or more, replace it to continue protection against corrosion; otherwise, other metal parts may be damaged.
 
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jbcurt00

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YES if there were anodes, now gone, definitely replace them.

Get the M & L 'toon stuff?
 

tablerockboater

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To update the OP, I did replace the deteriorated stringers and the transom, and all that appears to be working out just fine. I was concerned that the transom design was not right, but the motor sits in the water just fine, and trims out OK.

As for whether it will all last, time will tell.
 
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