Arwen's meanderings

Hi everyone and welcome to my dinghy cruising blog about my John Welsford designed 'navigator' named Arwen. Built over three years, Arwen was launched in August 2007. She is a standing lug yawl 14' 6" in length. This blog records our dinghy cruising voyages together around the coastal waters of SW England.
Arwen has an associated YouTube channel so visit to find our most recent cruises and click subscribe.
On this blog you will find posts about dinghy cruising locations, accounts of our voyages, maintenance tips and 'How to's' ranging from rigging standing lug sails and building galley boxes to using 'anchor buddies' and creating 'pilotage notes'. I hope you find something that inspires you to get out on the water in your boat. Drop us a comment and happy sailing.
Steve and Arwen

Tuesday, 9 April 2019

Dinghy cruising a John Welsford navigator - oar building update 3

Slightly colder - around 11C today but impatience set in. Lets hope everything cures OK.

So, using west epoxy 105 resin with 205 fast hardener.  Using the 1Kg of resin pack and mini pumps 301.  Basic rules about epoxy bonding as I understand them are below. It is many years since I have used the stuff so I had to do a little reading around.

First I prepared the wood by marking it out in 40cm sections and then rough sanding it with 80 grit paper and then a wire brush to rough up the surface. the marking out in sections helped me remember which bits had been sanded and not. It is soft Douglas Fir and so a good surface was established for the epoxy to bond to.

Then came the epoxy mixing in a plastic pot. I checked the rules once more on the can sides and leaflet. Because I am paranoid and wood and epoxy are costly!

  1. you can use it between 4C - 28C
  2. mix it in small batches and get it into a tray quickly so the heat dissipates rapidly and the open working time stays longer.  
  3. Mix thoroughly so that all the resin and hardener are truly mixed together.
  4. Wet out both planks to be bonded with a very thin layer first. Working at around 7C, I  had an open working time of around 20 minutes or so. I used a foam mini roller to spread put the epoxy in thin layers on both planks

         4. I then mixed another batch and added 403 microfibres to thicken the mixture. 
         5. This was then spread across one plank only and the two planks were then joined.
         6.  I then did steps 1 - 5 again with the two plank faces and added the final plank. 

          7.  I had already prepared the clamps and had opened them to the correct gap. They were
               added at 8 - 10" intervals both sides. I didn't bother to use plywood pads below as much
               of the wood where they attach will be cut off when I come to shape the oars. The trick is
               to clamp them with sufficient pressure without squeezing out all the epoxy. Easier said than

             8. I cleared up and removed runs down the sides after a few hours when it became rubbery.
             9. I'm now leaving the boards for around four days so they can fully cure. 

Further tips:

How I wished I had put down plastic sheet under the boards and along the garage floor. Dribbling epoxy went everywhere and its the devils own job to clear up. 

I should have used a couple of clamps over the width of the boards to stop them initially sliding about - would have made life easier. 

Next thing to build is a plywood jig for marking out the octagonal's on the oars when they have been cut to size in plan and elevation dimensions. 


Col Rodrick said...

Hey Steve

Noting your concern about epoxy drips under the oars you’re making, I have seen a video by Ross Lillistone(?) on easy cleanups. He used a heat gun and paint scraper. I have had the same drips in the spray booth where I poured ‘self-levelling’ epoxy two years ago. Problems: not self levelling at all, not drips but a veritable flood of epoxy.

Anyway, the video shows how to make short work of cured epoxy cleanup, without introducing toxic dust for your lungs. Spend ten minutes watching the video and a couple more sharpening an old paint scraper. Don’t wait years and then bury the epoxy under paint because you think it’s a lost cause like I did.

Best of luck with it.

PS love those Japanese pull saws. Mine goes with me as I visit the kids and mother in law. Easy to make neat cuts with little effort and no power required. Every home should have one.

steve said...

hey Col - how you doing? thanks for the video tip. As it so happens the drips chipped off with a chisel very quickly so I was quite surprised. I've just bought a scraper with carbide tip and that is also making short work of the dribbles. The Japanese saw - I confess I spent a very happy twenty minutes just using it to cut through some old off cuts i had in the off-cuts bin. So therapeutic :)