Second layer of Glass?

[Roel1]

Hello All,

I finished building my Ranger Canoe a couple of years ago. It was my first time building a canoe and was very pleased with the result. It turned out great and paddles like a dream. I chose to use only one layer of 6oz fibreglass all around, except for some bias strips at the stems.
Now I’m planning a trip with some friends in a remote area of Sweden. In the back of my head a thought keeps popping up; Will one layer of glass be enough? although we will be paddling on lakes and not rivers I wish I would have used two layers for the underside. I’d hate to have to repair a strip canoe in the middle of nowhere… My question is this; would it be possible (or wise) to add another layer - a football- to the underside of the canoe? Or will this second layer never adhere as good because it’s on the outside……


Hope to hear what some of the experiences are with adding a second layer.

Keep paddling and thanks,

Roel

[Patricks Dad]

If you are on lakes without a bunch of hidden rocks and you behave yourself, you should be fine with one layer of 6 oz glass. But Lakes vs Rivers isn't really the parameter you should consider. If the shores of either are rocky and you aren't paying attention, you can hit a rock in either environment. As for adding a 2nd layer, it would be possible to do so if you really want to. A second layer on the outside (football) will provide extra abrasion protection. If you want protection from an abrupt impact, you should add a layer on the inside. Be prepared for the additional weight that the extra layer(s) will add.

To add an extra layer, be sure to remove ALL varnish and get down to the bare epoxy surface. If you don't, you will have adhesion problems.

[Jim Dodd]

I double layer the bottoms of all my canoes, when I build them !
It not only adds wear resistance, but also adds stiffness.

You never know where a canoe will be used ! Why not build for rugged use ?

If you are just building a canoe for looks ? Skip the extra layer.
If you plan to paddle it ? Add the extra layer ! I've never regretted it !

[ID Canoeblder]

I also double layer the bottom football on the outside and on my 20 footer I doubled the inside as well. The canoe is twenty years old and had some delams last summer. I cut those out, sanded down and patched. The glass seems to be holding on to the existing glass very well.

If I were in your shoes, I would sand down the hull with 100 or 120 grit, being absolutely sure to get a consistent scratch (ie: no varnish shiny spots) over the whole hull. Put a football on the bottom, but bring the new epoxy all the way up to the gunwales so you don't have to worry about it fading in correctly. It should give you a nicer, easier finish and perhaps add a little strength up the sides.

Whichever way you decide to go, hope you have a great trip!

Greg

[Roel1]

Thanks for all the comments and tips. Really great!

I will add a second layer on the outside. Best way to do this would be to sand the whole outer hull as Greg suggests? Then add the extra layer (football size) and epoxe the whole hull to the gunnels?

Not so sure about the inside… Doesn’t the extra layer on the outside also offer impact protection?

Thanks,

Roel

[Patricks Dad]

Greg's advice for adding the 2nd layer on the outside of the football is sound. It will add abrasion resistance and stiffness. If you want to protect against impacts on the outside, you should consider adding a layer on the inside. If you think of the structure as an I-beam (two plates - layers of glass separated by a space - wood), the strength of the beam is a function of both plates. An impact from the outside will stress the inside "plate" as the force of the impact is transferred from the outside to the inside.

But of course doing any of this should be influenced by your intended use of the craft.

Enjoy the rest of your build.