let's talk under skinning

[bansil]

Google fu is not helping me I have read it here I am sure

Are you using 6061 or 5052? (i guess it depends on if you have to bend it or not)

What thickness? .032

it is mainly to keep splash from hitting the cross members and slowing you down and to keep water from coming up through the floors, so even thinner would work right?

I can get flat alum sheet already painted with a special polymer on both sides at .012 thick from local roofing manufacturer and have them cut 24 ft long and roll it back up, it is about 46 inches wide, and with a washer a rivet should hold it nicely with min. added wt

What you all think?

[Strake]

Having started my career in a Precision Sheet metal fabrication company, (many, many years ago), I'll throw in my 2 cents.....

I would use 5052-H32 which is a half hard, readily available (common) alloy alum. It can be easily formed.

Typically 6061 is used for heat treated applications like T4 or T6 which you won't bend well, or at all. A lot of traffic signs are made of this. If it is easy for you to get 6061 make sure it's 6061-0 which is "soft".

Another one to consider is 1100 -0 which is also dead soft and very easy to form.

As for thickness, I'm not sure what my factory under Skinned Berkshire has...... certainly not more than .032 but I bet it's more like 0.020" thick.

I'm not at our lake place now, so I can't check the thickness for you. You really need a micrometer to measure it correctly.

[bansil]

Machinist by trade...a long 25 years of it

I can get any flavor I decide to go with, I don't have my toon yet...just pictures got a couple more weeks wait

so I'm doing research

Does the skinning go down the sides a few inches to keep splash off top of tubes where cross members attach? (say rear half)


ETA fingers crossed...our future toon

[Strake]

If I was at our lake place, I'd take some pics for you...... but I won't be back there until the end of Feb.

The under skinning goes from tune, to tune with NO gaps inbetween. I do have a TRI TOON, so we have the port side pontoon log, then a curved " U shaped" piece of under skinning that butts right up against the log, to the center log and again butts right up to it. Same thing on the Starboard side. From underneath you don't see any exposed plywood base. It's either the aluminum logs, or the under skinning curved aluminum.

On our Berkshire, the under skinning goes all the way from the bow to the stern. The only area that is NOT covered is the outer two edges. That would be the outer side of each pontoon to the outer edge of the boat's decking.... It's about a 4 or 5" wide strip that runs the length of the boat on each side. Otherwise, everything else is skirted.

If you haven't started the project by the end of Feb....... post again, and I'll post several pics for you. Our boat is up on the lift, up high so I can get some pics easily.

Richard

[zoom650]

What thickness? .032
------------------

Went old school and measured my bow at 5/64th .. what's that, about .078?
Harris factory option for heavy water.

[Bryden24shp]

I wouldn't rivet it on, use sheet metal or Trex screws. That way you can remove panels to run accessory wiring or easily remove a damaged panel. My Manitou's were screwed on, the Premier's were not. The Premier was a pain in the butt to remove when I had to run wiring from the helm to the transom. Probably wouldn't have been bad if they used aluminum rivets, but the SS were hard to drill out and punch through to remove. I replaced the rivets with Trex screws. Took 10 minutes compared to 2 hours to remove the second time.

[willy13]

The under skinning I installed was .063 in the back and .040 in the front where there is much less splashing (5052 aluminum).

I was tempted to go thinner to save weight, but in the end chose not too.

[Soonertoon]

I used .080 material. No vibration or flexing as compared to thinner material.
Used a combination of 3M UV 4000 Marine adhesive ( this stuff is THE BOMB) and stainless TEK screws with an epoxy patch in the last three threads next to the head.
Many will say to use rivets but with this combination nothing should come loose or come out.

[bansil]

All Good points!!, didn't think about the force of the spray hitting and bending thinner sheet metal

So will probably look at .032 to start with, it is 24 ft, 2 toon's now and a 90...I don't see speed impacting the equation

Until we get it (if we get it, dont want to jinx fate) I will need to see how it sits in the water and such

[TDJ2591]

I used .063" 5052 aluminum. I wouldn't go any thinner. Search Underpinning on this forum and with Google for lots of info. I used 3/16" MagnaLoc aluminum large head structural rivets except for panels that I may want to remove for access. For those, I drilled and tapped for #8 SS screws with both SS flatwashers and neopreme washers. I also put thread lock on the tapped screws for added security against them vibrating loose. In my opinion, self-taping screws don't seem to have enough thread bite. I've read reports on here of self-tapping screws falling out.

[bansil]

Great update, thank you