fabricating your own aluminum gunnels?

[Seaspan]

Hello, I was hoping somebody could help me out. I am building small boats and have run into a snag. Buying the proper gunnel material from the factory is cost prohibitive. The options are at this point... using aluminum angle (which I think looks really hokey and bush league)

Does anybody have any ideas on gunnel construction? Or links where I could fabricate my own? I have a hand brake. Any ideas would certainly be helpful.

Thanks a million!

Seaspan

[JEM]

Buying gunnels for small boats certainly is not cheap. They can be very costly as a % of the total boat cost. For vinyl, it's near $100 per boat if you buy in small volumes

Some sort of aluminum extrusion would be the way to go. I'd be interested to see how this turns out.

[lalldrin]

I just bought a commercial fishing business in AK. I have a a pic of the skiff that came with the business. The gunnels are fashioned so that as the net passes over there is are no "net catchers" to snag the net. It is also boxed in to provide floatation. Having only seen this pic, I can't tell you how its made but I'd guess some alum tubing with flat stock welded on.

The pic I have is in a email sent to me by seller. I have saved it to my computer but can't get the link at the top of this page to accept the image. Any suggestions? Or get back to me with an email address and I'll send it to you.

Lance

[Seaspan]

Thanks for the responses gang. the aluminum extrusion is 65 dollars canadian for a 20 foot length...

20 foot length. To pricey. I did talk to a mill that would do small runs but I have to have the die made up. Pretty pricey until we get enough orders. Then it would be worth while...

rolledmuddler@hotmail.com

[Skippy]

To display a pic... (http://boatdesign.net/forums/showpost.php?p=44459&postcount=17)

[lalldrin]

Here is a pic of the shop built gunnel.

[Jack D Davis]

I'm considering using a suggestion from another designer. That is to take round tube and slot it lengthways with a saw. The kerf will slip right over the 1/8" aluminum edge.

http://www.hmds.ws/Gunwale Cap.jpg

[Thunderhead19]

Silver Streak does the same with square tube, it's easier to keep straight while cutting.

[Seaspan]

thank you all for helping me out. I have tried the cutting the tubing. Tough and tends to spring open. I might go back to that idea and give it some more thought.

Thanks gang.

[Jack D Davis]

Although I haven't tried it yet, my source tells me to clamp it between two 2x4's and use the 2x4's as a surface for the saw shoe plate and for using a rip guide.

Something like this??

http://www.hmds.ws/clamp.JPG

I would think it could be clamped along the gunwale to close the kerf up as you tack it in place.

[yago]

I have seen people try that on steel huls as well, but never quite got the idea why you should split it in the first place? why not weld it right on top?
What am I missing here? ;)

[Jack D Davis]

I've wondered that myself. The only reason I can think of is that the cut edge of the gunwale doesn't need to be perfect, so there wouldn't be any gaps to weld up??? If you can get a good fit, I'd think welding right on top would be the way to go.

[yago]

Jack, it might be easier to fair the top edge of the gunnel than to get 2 (!) clean edges both sides of the split tube... if it's an amateur hull and you have already built all the hull underneath it yourself, it really should not be a problem either way ;)

But what if you just want to get a a nice profile to bolt onto the sheerline of a wooden or GRP boat. I don't know of any nice, off-the-shelf adaptable alternatives to the yachtie stuff. Any ideas there?

[Seaspan]

I am a steel fitter for a big shipyard in Vancouver and all i do is work on steel hulls. All this stuff is relatively new to me. Splitting the pipe gives the side shell so much more rigidity.

[clearwaters]

Splitting the pipe is easy, just clamp it in a vise and get busy, The 2x4 idea is good.
The pipe being split makes for a very smooth curve, it makes it rigid and you DO NOT have to weld it all up. If you just put it on top you have to weld inside and outside.
We have been doing this forever on drift boats.
You can't do it on steel since the rust will always be there.
Keep the wire moving. Gary

[Jack D Davis]

Now we know. Thanks, Gary. I'd say the round tube is easier to curve than square, too. It will curve in any direction and square or rectangular, due to its shape, is limited.