Capt. Pat... StarBoard/SeaBoard fabrication questions...

[IRGuy]

With a full woodworking shop and a project boat I plan on doing some HDPE board fabrication... and have started to look at welding and adhesive issues. It seems there are a lot of biases and misconceptions floating around about joining these materials.

1 - Have you worked with either of these products? Both are HDPE, but I am told StarBoard is more difficult to weld than SeaBoard.

2 - Do you have any experience welding these materials? I have seen hot air welding systems ranging from a few hundred to several thousand dollars. A lower priced system is not out of the question for me if I thought it would do a good job.

3 - I am told there are some two part adhesive systems available that do a good job of joining these materials, and in fact am getting ready to test two, but would like to know if you have any experience with adhesion as opposed to welding.

Any comments you or anyone else here might care to make would be very much appreciated!

[CaptPatrick]

The first thought that crosses my mind is, that for most marine applications, all HDPE, (high density polyethelene), suck...

The biggest problems arise from the instability of the material, where expansion and contraction are concerned, the difficulty to effect any kind of a structural bond, and low alility to tightly hold screws.

Add to this that the material is very expensive and relatively heavy. It's easily marred, and difficult to refinish. It gets dirty looking quickly & if the surface isn't perfectly smooth, dirt and grime get imbedded into the surface scratches. Very difficult to keep clean looking.

Welding HDPE does require a decent hot air welder. I have one that cost around $300.00. Much less than that price range is pretty much a toy & much more expensive is for the guys fabricating for a living.

The welds are not pretty... Basically a melted in filler rod, leaving a very noticeable bead. Nothing like a weld on metal with a TIG torch. The learning curve to get good quality strong welds is large.

If the intended purpose involves a surface to be stepped on, (step pads, ladder tread, deck hatches. etc.), be sure that you have a large paid up liability insurance policy. HDPE is slicker than deer guts on a door knob & someone's gonna' end up getting hurt.

There are some adhesives that lay claim to being able to bond HDPE, but all that I have seen don't chemically cross link the material together. Certainly not good enough for a structural bond without additional fasteners. Light weight trim pieces, like a facing for a cabinet can be held with 3M 5200 provided that the bonding surface is heavily abraded to create a tooth for the adhesive to grip into. You can also cut angled kerfs & dove tails into the bonding surface for added adhesive grip.

Our own Faithful Mitch tried making a large HDPE hatch cover over a fuel tank on the B28 he owned before his B31. He can affirm, from first hand knowledge, what a nightmare the expansion and contraction issues are. Basically any thing made in HDPE with a dimension over 1 foot and expected to retain it's assigned place is folly.

The short answer is that HDPE makes wonderful throw away cutting boards, can be used for small backing blocks for through hull fittings, and beyond that you'd never find the stuff on any project I did...

Br,

Patrick

[IRGuy]

Gee Capt... It is a shame you don't feel free to speak your mind! Seriously though I do very much appreciate your comments. I am looking for stuff I can use for things like a bait well and tackle station and lockers to slide in under the cockpit coamings of my B31. Is there another low maintenance sun and seawater tolerant material you would recommend? And if so, how would you suggest adddressing the issues of making joints with it?

Thanks... Frank

[Rawleigh]

PVC board is his favorite, but I'll let him tell you about it.

[Doug Crowther]

Patrick how do you really feel ?

LOL

[CaptPatrick]

Doug,

About like the day you arrived at Ft. Liquordale with the cute little blonde. Some things just light my fuse...

Frank,

with regards to the PVC Foam Board that Rawleigh mentioned, see: PVC Foam Board as an Alternative to Plywood

Br,

Patrick

[Harry Babb]

Thats my kind of response Patrick.............Opinion backed up with fact and experience............

I didn't have to read between the lines......I understand exactly what the man said.

We machine some parts out of UHMW.........I am not sure but I think that its about the same stuff.........Patrick is right about keeping it looking good real pain in the ass

Harry Babb

[IRGuy]

Capt Pat...

Thanks for the reference.. I recall reading it before, a long while ago.

It is interesting to note that you are recognized by Google.. when I Googled "PVC foam board" your article was right up at the top of the first page!

[CaptPatrick]

Harry,

UHMW stands for Ultra High Molecular Weight. It and HDPE are same except for density; both polyethelyne...

Frank,

Yeah, I'm way too easy to find any more. So much for anonymity & low profiles...

If you have a problem finding PVC Foam Board, call Mike at Sun Ray Plastics, (phone number on the PVC page), and he may be able to give you a source near you. He'll also ship anywhere & his prices are often better than the competition, but then you've got shipping charges to deal with.

Br,

Patrick

[IRGuy]

Capt Pat...

Anyone with a beard and hat like yours can't stay off the radar screen!

Thanks for your help!

Frank