Replacement gunnels out of 3" square housing pvc pipe?

Thanks for your input,I think round pipe fibreglassed over would be vulnerable to cracking if the gunnel got bumped.
I will be trying to get the least joins as possible in the gunnels,so each side would be about 11ft allowing for the curvature.
I have plenty of time on my hands,so I could f/glass in short sections,and only heat about 2ft at a time,the clamps would be on the cold sections of the pipe,
either side of the heated sections.

 

Nice little dinghy project pic,I put the gunnels on a boat using 'F' clamps the same as you have there.I used steam and clamps and ss nuts and bolts to follow the curvature.
I have a propane torch with six different heads,so long as I didn't melt through the pipe,a little discolouration would be covered by the fibreglass and gelcoat. Good idea,thanks.

 

I prefer to have the gunnels on the outside of the boat,I don't think I need an inner strengthening strip on the inside.If I was using timber,I definately would have an inner and outer.
Re the Dinghy seat,on a small dinghy,I think a gunnel to gunnel seat would be better,(plank)simply because of the balance,A central bow to stern seat would get in the way and restrict the legroom,and restrict the deck space.A sliding fitting on the plank would allow for adjustment for different leg lengths.

 

Not my build, just a pic I lifted to illustrate the gunnel detail, its easy and adaptable.
I’ve built many small boats like that, laminating 1/4” strips can make tight curves easy..
Maybe that’s the bow of a jonboat with a float chamber?

 

My experience is that the square/rectangle will be far more likely to crack after impact than a round profile.

I suggest spending some of your abundant time doing a test by glassing over three foot long pieces of both square and round PVC tubes.

Fiberglass simply does NOT do square corners! ! !

 

I'm a little confused at why round would be more susceptible to cracking than square.

In one application I used to cut slots with a circular saw on one side of the pipe so it would bend to follow the radius, then glass over it.

 

Whats up with the PVC proposal. A one and a half by three quarters wooden strip will make a perfectly suitable sheer strip. Builders have been using that, or something dimensionally similar, for a few hundred years. It works. It is simple. It is not difficult. If the boat is to engage in maritime warfare, the 1.5 x 0.75 strip can be doubled with another layer so as to present a 1.5 square sheer strip. That would be useless overkill for a 10 foot boat................except of course that it is to be a warship or perhaps a tug boat.

 

Thanks,I'll give that some thought.

 

That's a good idea,I think I will probably do that.As for round versus square,with round pipe it would need a fillet on top,and a fillet underneath.
The whole idea is to lighten the boat,and to have dry gunnels.The topside of the gunnels will need to be square to the hull.

 

Thanks for the suggestion,I can get hold of double glazing pvc strips that would be perfect.(window reveal strips)
I am trying to avoid timber to keep the weight down.It's not exactly a warship,haha,but it's a tough little manoverable and stable boat.
It rows effortlessly,and will turn easily in it's own length,and with a 6hp outboard on it it semi planes.
I already have speedboat on my drive (Broom) so I need to get the rowing boat off the trailer and down a passage to store them both.
I seem to have mislaid my pics of it on the pc somewhere,and it's got a deflated 9ft rubber dinghy on it covered with a sheet at the moment.

 

How is that going to work? Timber is light, stiff, and strong, PVC is heavy and needs fiberglass over it to be stiff enough.
Cut the existing structure away, epoxy a DF strip on the inside or outside (as you like) and paint. Does not get much lighter unless you go to foam/carbon.

 

here's the rowing boat

 

He means PVC tube, obviously.

 

The keel and stabilizers are hollow,and the f//glass is about 5mm thick.(Warship or what?) haha.

 

If all you need is a former, use foam.