Doing the splits !

And not in a good way either.

Blog time : as i take a break it’s a surprisingly cool to cold morning right at the end of August 2021 – a cold wind from the east i think is the problem. Anyway, first thing this morning i went out to check my work from yesterday and found if not an epic disaster but a sickening setback : i found all of the clamps that i’d set across the back of the boat to pull the bilge stringers in all slack and when i looked i found that the port side bilge stringer had cracked and split right through. The split was about 2 feet long and i thought that i might be able to rescue it by gluing it back together, maybe flipping it over and trying again but then, as i eased the clamping pressure and then released the clamps the split just ripped along the length and that one stringer is now 2 pieces and definitely beyond recovery.

Or so i thought…..

On the bench.

Yesterday then i decided to tackle one of the hardest jobs in the build (for an non boatbuilder) and that job being to bend the 2 bilge/chine stringers around the frames and set the stringers into the frame notches. Anyone here who has built similar boats or dealt with the same problem will instantly see the potential problems but for other backyard beginners whom are following the build and haven’t come across the problem i’ll try to explain.

So, the bilge/chine stringer is a long length (6.1 meter) of 75mm x 20mm Douglas fir that has to be bent around the total curve created by the frames. Now, most people would quickly work out that a piece of timber will bend fairly easily in one plane but will be a lot stiffer across it’s width….in fact one thing it will always try to do under edge force is translate some of that force in bending the ‘easy’ way and unfortunately it can’t be allowed to do that because it has to marry against a surface that is essentially flat . Yes, there is some curvature in the bottom board but the main bend is across the stringer width – in short this is ‘edge’ bending the timber.

Second attempt.

I posted a couple of photographs on the designer’s forum and most people said ‘ouch’ but that it might be feasible to glue the piece back together because the split, although ragged, is only like a long scarf ; in fact it’s about an ideal scarfing ratio. So i did that – glued and clamped in both planes and left the whole thing to set for 24 hours ; then i had a further brainwave and laid a long length of GRP bandage along the length of the repair….at least along both faces and the outer edge. I left that again and came back to it a day later when i once again tried to bend both stringers around the boat : the starboard (good) side went in to about 50mm away from where it needed to be at the transom and just really hardened up at that point. The port side (broken/repaired side) went in to a bit more than stbd and then also hardened up a lot….it felt that i’d put about the maximum force on at that point.

Then, i thought it best to take a break and come back to it in about another hour and see if either side would pull in a bit more ; i was just relaxing a bit when there was an almighty bang from t’other side – my partner heard it from a hundred feet and inside the cottage away. It was the broken/repaired stringer again and this time it went through completely and not just a simple split in one run of grain but several….like an ugly compound fracture in a long bone.

“And that’s all she wrote”…..!

All that i could do was slowly ease all of the clamps off both sides , take the good side off and stow it back under the boat and see what if any wood i can rescue from the broken side : the answer there is that i can recover a few bits that will get cut down for blocks and bearers. The next stage is to think again and try a different technique – forum members are mostly agreeing on laminating the stringer from 3 pieces : i could perhaps make a couple of lamells from the good side but it will be very difficult to control that length of wood through the table saw and i’d lose a lot of wood to the blade kerf. What iv’e done is ordered 6 lengths of new timber at 20 x 25mm and my intention is to laminate the bilge/chine stringer in situ. I might or might not need to steam the new stock – most builders are saying not…..but it might pay to steam the upper stringers before i try and bend those around the frames……so my next task is to build a steaming rig.

1 Comment

  1. No one said it easy going to be easy eh Steve! Pity about the time and extra expense but I have every confidence that you will prevail in the end.

    Like

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s