Need help choosing seam sealant on aluminum sailboat

[Thaddeus]

Hi,

I am building a fast sailing dinghy out of aluminum. I am using an aluminum canoe hull as the basis. Pics at http://www.tc.umn.edu/~austi012/sailboat2.htm.

I am waiting for my special order rivets to arrive, so I have some time; but I am uncertain what sort of sealant to use on the seams. Can anybody suggest something? It almost looks as though Alumacraft used pipe dope on the original seams. I'd need something tough, watertight, resilient, and resistant to extremes of temperature, and of course it should stick to aluminum.. Would something else be a better choice? Silicone caulk, perhaps?

Thanks in advance for any help anybody might be able to provide.

cheers

Thaddeus

[Thunderhead19]

Uhhg....oh well, use Sikaflex 292 or equivalent (like 3M 5200). Make sure the parts are clean and clamp then together lightly. Don't use too thick a bead or it will never cure properly.

[Thaddeus]

Why the "Uhhg...." ?

[vishnubaiju]

Are you going to provide more stiffeners inside the hull. The existing stiffeners were for a narrow boat. Now the width has increased. So more support required in the bottom and sides. What about a watertight chamber inside.Is the aditional center plate (new one) thicker than the sides?
NICE IDEA of widening.
I was thinking in a similar fashion for my Aluminium boat to widen it. It is a welded craft. I will do it.

[BillyDoc]

Hi Thaddeus,

If you clean the aluminum very thoroughly, many 100% silicone based aquarium sealants will chemically bond with aluminum (and glass). Find a Wal-Mart and check out their pet supply section.

You might want to get some of this sealant and experiment with the particular alloy you are using. If you are using lapped seams, for example, the sealant will probably be stronger than any rivet. The stuff is also very tough. I use it for all sorts of things. To clean the aluminum, a fine wet sanding using a detergent solution, followed with a rinse and acetone wipedown usually works . . . if you keep your fingerprints off!

Bill

[Thaddeus]

Now I know why the 'ugh'. I set about 250 rivets today. Tomorrow I will be drilling out about 30 to redo them... sigh.

New pix on the updated website referenced above, if anybody's interested.

[Thaddeus]

man what a lot of rivets.



I am making a hollow daggerboard out of aluminum... the idea is that it will fill with water when submerged and provide additional righting moment (not much; about 25 lbs. when the boat is at 30 degrees of heel... but every little bit counts in a boat that is only going to weigh about 140 lbs).




Still a lot of hammering to do on the daggerboard. It's not nearly finished.

[stonebreaker]

Originally Posted by BillyDoc

Hi Thaddeus,

If you clean the aluminum very thoroughly, many 100% silicone based aquarium sealants will chemically bond with aluminum (and glass). Find a Wal-Mart and check out their pet supply section.

You might want to get some of this sealant and experiment with the particular alloy you are using. If you are using lapped seams, for example, the sealant will probably be stronger than any rivet. The stuff is also very tough. I use it for all sorts of things. To clean the aluminum, a fine wet sanding using a detergent solution, followed with a rinse and acetone wipedown usually works . . . if you keep your fingerprints off!

Bill

Why would you want to use aquarium sealants? they're exactly the same thing as the 100% silicone you get at Home Depot except the aquarium sealants don't have mildew inhibitors in them.