Help repairing crack in polyethylene canoe
Posted: Tue Feb 18, 2003 6:46 pm
Help repairing crack in polyethylene canoe
by M. Gray M. Gray
I seem to have developed a craack in the inner hull of my polyethethylene sandwich type canoe.
Can anyone give me advice on how to repair this?
Also, can anyone tell me where I can get the neccessary materials/supplies to do the repair?
Posted on Sep 15, 2002, 10:53 AM
Repair to polyethylene canoe
by Daniel Holzman
From your post, I assume that you have a crack on the inside of the boat which does not extend through to the outside - either that or you are paddling a double hulled canoe, which would be a true oddity. The method of repair depends to a large extent on the type of polyethylene in your boat.
There are two basic types of polyethylene, cross linked and straight chain (also known as linear, or sometimes called super linear). Most boats older than two years are cross linked, while current production boats may be cross linked or linear. You can't tell by looking at the boat, the manufacturer needs to tell you what type of polyethylene they used.
Linear polyethylene can be welded using a hot air gun. I don't recommend you try this for the first time on a boat you want to continue using, you need to find someone who has actually done the job before. The process involves heating the polyethylene near the melting point, and using a polyethylene welding rod to melt into the crack. I suggest you call your local marine supply store, or a plastic distributor, to see if there are any polyethylene welders in your area.
This process apparently does not work on cross linked polyethylene; I am told that you cannot weld it. I once tried to repair a small tear in a cross linked polyethylene boat of mine using a P-tex stick normally used to repair the base of a ski, and the result was totally unsatisfactory, no bond, just more damage. I finally repaired the resulting damage using epoxy putty, which actually held very well, even though the manufacturer specifically stated that their particular epoxy putty did not bond to polyethylene.
If you have a cross linked boat, I suggest you put a fiberglass patch over the tear. Fiberglass does not normally bond well to polyethylene, however you can improve the bond considerably by sanding the polyethylene first, and running a propane torch over the area of the tear VERY LIGHTLY (you are not really trying to heat the polyethylene, just get the surface molecules a little agitated so they bond better). Use a high quality epoxy resin such as West Systems, use a tough glass like S glass or Dynel cloth, and make sure that the polyethylene is at least 65 degrees F when you do the repair. Since the bond is poor, you should use a reasonably large piece of cloth to get more bonding area. You can get all the supplies you need from John Sweet out of Mustoe, Virginia. He has a web site, but you need to call him to order supplies.
Good luck.
Posted on Sep 17, 2002, 10:08 AM
polyethylene?
by Scott Broam Scott Broam
When you say "sandwich" that sounds like royalex, which is a sandwich of vinyl (outer layers), ABS(under the vinyl, outer and inner), and foam (about 1/4" in the middle). If you have a canoe by Dagger, Mohawk, Mad River, Blue Hole, or Old Town (some of their boats), it is probably Royalex. If you boat is by Coleman - you have a single layer of polyethylene; Old Town does make two kinds of polyethylene "sandwiches" (Superlink3 - cross link, Polylink3 - linear) - see the previous post or Old Town's page for some materials : https://www.oldtowncanoe.com/cgi-local/ ... y&cat_id=9
Repair of that Royalex is a bit different than polyethylene - I do NOT think you would want to weld it. You could use a fiberglass/kevlar patch, ABS putty , or PC-7 (at hardware stores). I've had good luck using ABS - you can buy sheets of ABS and ABS cement from plastic supply houses.
HTH -
Scott
Posted on Sep 17, 2002, 11:52 AM
by M. Gray M. Gray
I seem to have developed a craack in the inner hull of my polyethethylene sandwich type canoe.
Can anyone give me advice on how to repair this?
Also, can anyone tell me where I can get the neccessary materials/supplies to do the repair?
Posted on Sep 15, 2002, 10:53 AM
Repair to polyethylene canoe
by Daniel Holzman
From your post, I assume that you have a crack on the inside of the boat which does not extend through to the outside - either that or you are paddling a double hulled canoe, which would be a true oddity. The method of repair depends to a large extent on the type of polyethylene in your boat.
There are two basic types of polyethylene, cross linked and straight chain (also known as linear, or sometimes called super linear). Most boats older than two years are cross linked, while current production boats may be cross linked or linear. You can't tell by looking at the boat, the manufacturer needs to tell you what type of polyethylene they used.
Linear polyethylene can be welded using a hot air gun. I don't recommend you try this for the first time on a boat you want to continue using, you need to find someone who has actually done the job before. The process involves heating the polyethylene near the melting point, and using a polyethylene welding rod to melt into the crack. I suggest you call your local marine supply store, or a plastic distributor, to see if there are any polyethylene welders in your area.
This process apparently does not work on cross linked polyethylene; I am told that you cannot weld it. I once tried to repair a small tear in a cross linked polyethylene boat of mine using a P-tex stick normally used to repair the base of a ski, and the result was totally unsatisfactory, no bond, just more damage. I finally repaired the resulting damage using epoxy putty, which actually held very well, even though the manufacturer specifically stated that their particular epoxy putty did not bond to polyethylene.
If you have a cross linked boat, I suggest you put a fiberglass patch over the tear. Fiberglass does not normally bond well to polyethylene, however you can improve the bond considerably by sanding the polyethylene first, and running a propane torch over the area of the tear VERY LIGHTLY (you are not really trying to heat the polyethylene, just get the surface molecules a little agitated so they bond better). Use a high quality epoxy resin such as West Systems, use a tough glass like S glass or Dynel cloth, and make sure that the polyethylene is at least 65 degrees F when you do the repair. Since the bond is poor, you should use a reasonably large piece of cloth to get more bonding area. You can get all the supplies you need from John Sweet out of Mustoe, Virginia. He has a web site, but you need to call him to order supplies.
Good luck.
Posted on Sep 17, 2002, 10:08 AM
polyethylene?
by Scott Broam Scott Broam
When you say "sandwich" that sounds like royalex, which is a sandwich of vinyl (outer layers), ABS(under the vinyl, outer and inner), and foam (about 1/4" in the middle). If you have a canoe by Dagger, Mohawk, Mad River, Blue Hole, or Old Town (some of their boats), it is probably Royalex. If you boat is by Coleman - you have a single layer of polyethylene; Old Town does make two kinds of polyethylene "sandwiches" (Superlink3 - cross link, Polylink3 - linear) - see the previous post or Old Town's page for some materials : https://www.oldtowncanoe.com/cgi-local/ ... y&cat_id=9
Repair of that Royalex is a bit different than polyethylene - I do NOT think you would want to weld it. You could use a fiberglass/kevlar patch, ABS putty , or PC-7 (at hardware stores). I've had good luck using ABS - you can buy sheets of ABS and ABS cement from plastic supply houses.
HTH -
Scott
Posted on Sep 17, 2002, 11:52 AM