Join Date: Jan 2003
Location: Maine Coast
Thanked 310 Times in 240 Posts
Rep Power: 18
No need for 5200
you already have a mechanical seal! 5200 is a totally over rated product and the biggest scam put forth on the uneducated boating public I've ever seen. The ONLY place for 5200 or any product like it is a keel joint and even there I'd use Sikaflex over 5200 because it remains more flexible than 5200. Even a hul to deck joint will flex to much for 5200 over the long term. The three products I'd use would be UV4000, 101 or "Sikaflex 291 LOT" with the edge going to 291 LOT. All these products have better flexibility for the expansion / contraction between the wood and fiberglass than does 5200. 5200 is for boatyards who want future repair business or novice boaters who know no differently. I know quite a few of the top quality yards here in Maine use Sikaflex exclusively and NOT 3M 5200. Sika Flex 291 LOT has a 700% elongation at break while according to 3M 5200 is 350% so 291 is twice as flexible. Flexible is what you need between dissimilar products like wood and gelcoat.
Noting and I repeat NOTHING on a boat is a permanent seal. Trust me I had to re-bed my keel that was originally bedded with 5200. Once the keel bolts were loose they jacked my boat up but the keel was still holding on in certain areas. After letting it hang for a few days they began with Oak wedges. No Luck! They actually had to use a sawzall to get my keel off in the end. The problem was when they got about half way through the weight of the keel literally ripped and delaminated the fiberglass keel stub. They then had to repair that. The keel on that boat was put back together 10 years ago with Sika Flex NOT 5200. The reason it needed to be re-beded in the first place was because it was not flexible enough after a few years and began leaking! Don't believe me here's what 3M has to say..
"Because 5200 is so strong and its primary use is for permanent applications like those in hull-to-deck bonding, 3M introduced 4200, which is about half as strong and is more suitable for general-purpose applications. “If you want to get [the adhesive] off, go with the 4200, says Dewey."
5200 is one of the few products that will NEVER set foot on my boat Sikaflex is more flexible over time and more than strong enough for ANY boat application. Sikaflex 291 is about the same adhesion as 4200 but more flexible!!
-Maine Sail / CS-36T
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