Bonding Starboard(Plastic Lumber) to a C-Dory

CAVU

I have a question for the great minds who frequent this group: can Starboard be glued to the C-Dory hull (inside)? I recently bought a piece of this material at West Marine and the instruction sheet indicated that 3M 5200 would not bond to it! My idea was to glue a piece of this to the inside of the hull and then atch fittings, etc. to the starboard without drilling holes in the boat. Has anyone had success using this material and if so, what did you use as an adhesive? Any other ideas would be appreciated. Thanks.

Anita Marie · Posted: Thu Aug 19, 2004 11:51 pm Post subject:

Ken I have glued starboard to the fiberglass inside the cabin with 3M4200 with success. http://www.c-brats.com/modules.php?set_albumName=Cabin,Interior&id=Cabin_Interior_004&op=modload&name=gallery&file=index&include=view_photo.php
I had problems at first with it not adhering. I took my rotozip and set it at 1/8" and just made a bunch patterns on the side that you would put the adhesive on. Then just put a healthy bead of adhesive in the grooves and it bonds just fine. Make sure you brace it for at least 24 hours, my bow hook worked just fine.

Fred

MOOSE · Posted: Fri Aug 20, 2004 9:30 am Post subject:

You raise a very good question that I, too, would like to know the answer to. I suspect that, despite etching a pattern into the backside of the Starboard to provide more gripping surface area, you'd still be able to rip the piece off with your bare hands. At least that has been my experience. WM does sell some adhesive that is supposed to bond with Starboard, but it's fairly expensive (about $35, if I recall). One could screw thin strips of teak onto the backside and then bond to that. Anyway, just some random thoughts. I love Starboard, but have generally resorted to screwing the stuff together.
Al

CAVU · Posted: Sat Aug 21, 2004 11:15 am Post subject:

Thanks for the info. Moose I think the idea of mechanically attaching wood strips to the starboard and then bonding the wood might work for me. I want to atch some narrow strips to the inside of the hull in the cockpit under the shelf on each side. My idea was to use the strips to mount holders for my boat-hook on one side and my gaff on the other. I suppose I could just bond a teak strip to the hull to use as a mount, but the starboard would be a better match to the rest of the cockpit.

thataway · Posted: Sat Aug 21, 2004 9:05 pm Post subject:

A trick which has worked with some other materials like starboard is to use a router with a dovetail bit--this bit is tapered, so that the surface is narrower than the deeper part of the cut--this gives a real tooth for the 5200 to adhere to.

Blueback · Posted: Fri Dec 13, 2013 11:51 pm Post subject: Glue ? re; starboard

I have been researching this and the product was right in front of me but none of the marine dealers could give me the answer.
First flame treat the bonding surfaces-- yellow part of the flame, 2 or 3 brush passes only. Test with water and if its properly flamed the water will not bead up. Wipe dry then apply "Loctite" Plastic glue for polyethylene-- it all so glues polypropylene too. Loctite to the rescue---eh

thataway · Posted: Sat Dec 14, 2013 12:40 pm Post subject:

Which specific Loctite product are your using? Have you done destructive testing--if so what is the yield force?

King Starboard has had specific instructions for gluing the High density polyethylene products using the flame process on their web site for some time:

http://www.kingplastic.com/using-adhesive-with-king-starboard-2/

Blueback · Posted: Tue Dec 17, 2013 12:27 am Post subject:

[quote="thataway"]Which specific Loctite product are your using? Have you done destructive testing--if so what is the yield force?

King Starboard has had specific instructions for gluing the High density polyethylene products using the flame process on their web site for some time:

http://www.kingplastic.com/using-adhesive-with-king-starboard-2/

thataway · Posted: Tue Dec 17, 2013 5:47 pm Post subject:

Blueback, Thank you. It would appear that the materials in the Loctite 770 (polyolefin primer for cyanoacrylate adhesive) is very similar to the "activator" and the materials in the Loctite 401 is similar to the glue in the Loctite Plastics Bonding System (from the MSDS)--which comes in a small container or 4 grams of Activator and 2 grams of Adhesive. One item which concerns me is that the Plastics Bonding System states not for external use. The 401 appears to loose 50% of its strength if exposed to water for a long period of time. Also these are both cyanoacrylate adhesive so that you have to have a very good match of surfaces. There is little if any filling effect of the cyanoacrylate adhesives, vs epoxies or urethanes.

In other words, if you want to use this system to "glue" Starboard onto the side of the cabin, you would have to have a very good match, with almost perfect fit.

The Handbook of Plastics Joining validates what you found form Loctite, (50 PSI for 401 alone, 2000 PSI for combination of 770 and 401). However this is for HDPE to HDPE--the best method is various forms of heat welding--which gave yields of 2050 PSI to 4000 PSI depending on the specific composition of the HDPE. The advantage of heat welding is that it will be waterproof, vs the adhesive, which does loose about 50% of its effectiveness over time when exposed to water. It would be interesting for someone to glue Starboard or some other HDPE to the fiberglass of the inside of the cabin and see how it works using this cyanoacrylate adhesive.

Blueback · Posted: Tue Dec 17, 2013 6:39 pm Post subject:

bridma

Blueback

thataway · Posted: Tue Dec 17, 2013 9:51 pm Post subject:

Heat welding only applies for HDPE to HDPE joints. Some "glue" method might work for the transom piece.
There is the "Stern Saver", which uses a temporary "stick on spike" to hold the piece of HDPE in place, until some thickened epoxy (probably G Flex?) which is put into 6 holes, which have ridges machined into the sides, to give the epoxy something to grip on.

There is the "Stern Mate" which also uses a thickened epoxy--don't know if there are cuts, holes or slits in the HDPE or not--but suspect there are.

I don't know if the Loctite system would work flat against the transom--the transom should be flat--the starboard should be flat--and there may be enough contact area, if you can hold the Starboard to the Transom for at least a few minutes (Although it should give almost immediate adherence, Loctite suggests clamping for up to 24 hours for full cure) However there is that warning about outdoor use, and immersion in water...

My personal experience with Starboard is that I am not convinced that a block would be sufficiently adherent. I have used a dove tail bit and cut grooves which I think would be sufficient to hold it with 5200. But in most of the cases when I put a Starboard Block on the transom, there were already screw holes, which I drilled out, undercut and filled with epoxy, then installed two screws thru the Starboard into the epoxy plugs.

Why I don't put the transducer bracket screws directly into the transom: First often you need to move the transducer to get the best image on the fish finder, second you may change transducers, third, I have seen a number of boats with water intrusion into the transom form the holes holding the transducer in place.
Example:

There are other materials, such as PVC lumber which will glue will to the gel coat and can be used instead of HDPE.

As for sealants, I feel that I am pretty much on or ahead of the curve with the proper use of sealants…It is fine if you get good prep, into a solid area of glass. But often screws loosen a bit, or they are loosened to move the transducer--and when put back--do not have a good seal--and transom rot is the result.