Sealant for transom bolts

[Acme54]

I finished refurbishing my 1957 Lonestar Admiral Deluxe and will be installing a new 25 HP 4 stroke this spring. It requires transom bolts and don’t know what sealant to use for the bolts. Any ideas would help. I have seen a few negative things about 5200 and aluminum. Thanks

 

[Zip]

I have always used a flexible sealant, specifically Life-Calk for transom bolts. Never a hard sealant like 5200.

 

[mbullen]

fwiw, 5200 remains flexible, in my experience. It's the industry standard for permanent sealant. 4200 for semi-permanent.

 

[DaleH]

Life-Caulk or 5200 ... just make sure the tin is primed first. Or to be cheap ... yet it works, apply duct tape in area, add nylon washer under the SS bolt heads and washers, then apply the goop. Can trim off any tape that shows later. It will insulate the tin from the corrosive effects of the goop curing agent.

 

[LDUBS]

Nothing is as versatile as good ol duct tape!

 

[MN Fisher]

Nothing is as versatile as good ol duct tape!

 

[Tin Man]

X3 on Boatlife Life-Calk. It is a polysulfide sealant and does not harden. Not cheap, but a very good product.

 

[Acme54]

I have always used a flexible sealant, specifically Life-Calk for transom bolts. Never a hard sealant like 5200.

Thanks for the help. My first aluminum boat so don’t know much.

 

[Acme54]

X3 on Boatlife Life-Calk. It is a polysulfide sealant and does not harden. Not cheap, but a very good product.

Looks like what I need. Thanks

 

[DaleH]

FWIW I use both the polysulfide products of 3M 5200 and the Boatlife Life-Calk. I can get the BL tube much cheaper and it lasts for years, whereas 5200 will dry up. I will admit I do find 5200 to be a little more 'tenacious' and I will use for underwater fittings. But otherwise the BL is my 'go to' sealing goop.

 

[hennessyktm]

After tons of research, I used 4200 on a 15' x 5' aluminum boat I just rebuilt so I could remove the bolts in the future if I ever needed to. Holding up great, zero leaks.

 

[thill]

4200 if you want to be serous, but defintely not 5200.

Life caulk is a good choice. I use the Loctite brand marine sealant sold in the big box hardware stores, or seal with clear silicone. Have never had an issue in any of my boats.

 

[AlanT]

4200 if you want to be serous, but defintely not 5200.

Life caulk is a good choice. I use the Loctite brand marine sealant sold in the big box hardware stores, or seal with clear silicone. Have never had an issue in any of my boats.

Just curious. Are you saying 4200 has better holding power than Life Caulk? I've never used Life Caulk, so I have no frame of reference.

 

[Bass Tracker 93]

Is 100% silicone not acceptable? I'm about to do this project as well and use GE 100% silicone that says it adheres to aluminum.