A nice question and answer on the Goat Island Skiff group on Facebook about inwale spacers. The regular gaps in the photo below. And a nice method to solve the problem!
These nice spaces created along the gunwale add a lot of appearance to the boat. But how to space them correctly.
Inwale spacers on boats can be highly functional
Eureka Canoe FP – spaced gunwales for appearance and stiffness.
Inwale spacers have three main functions
- Make the gunwale massively stiff so the rest of the boat can be lightweight – almost “hung” from the gunwales.
- Save weight despite the massive stiffness.
- Look pretty – it harks back to the inwales being fitted over the top of ribs in a traditional type boat. It looks kindof “right” to most people’s eyes.
- Allow water to be poured completely out of the boat when it is layed on its side – no water gets trapped underneath a solid inwale.
However the inwale often has a bunch of functional requirements as well.
It might have to meet knees at the bow or at the transom. Goat Island Skiff built by Peter Hyndman.
It might have to be solid at oarlocks (normally a foot behind the back of the rowing seat) or match the frame heads. Where oarlocks are fitted I really recommend a one or two flathead screws be put into the face of the inwale, go right through the inwale spacer and well into the gunwale to prevent the timber splitting.
Another place that might require a block is in the way of stays to support the mast or where the mainsail traveller will be attached if it is a rope traveller that runs across the boat at gunwale level like the GIS.
No – you don’t need many clamps
Mark Nye posted a photo of his building progress showing the inwale spacers just being finished.
It is actually a nice place to use the cheap PVC pipe clamps. In general I don’t use many clamps … just use drywall/plasterboard screws to hold things together while the epoxy sets up. I have the philosophy that apart from the most simple dugouts, the history of boatbuilding is the history of holes.
The modern tendency to try to avoid holes is from the furniture tradition – yep those things that you can rip apart with your bare hands or with a kick in the right place. Nothing to do with boats.
Al Bono on the Goat Group asked – how to get the inwale spacings right?
Mark Nye replied just a few minutes later (one of the big benefits of FB groups – there is always someone awake!) …
I place forward most, aft most and oarlock spacers first, then played with positioning to avoid bulkhead frames and get even spacing. I marked spacer positions with pencil and blue tape on top of shear.
So idea is to look at the construction requirements first and place those inwales spacers first, then some calculation and check by trial and error using tape markers that are easily moved.
Another way of spacing around the frame heads that also space the gunwales is to put a part spacer next to them or on both sides of the frame head so that the frame head looks much like a gunwale spacer.
Simon Lew from Florida added another method when I posted this article to the Goat Island Skiff FB group – thus proving the value of such a group – to hide the frame heads completely if wanted.
He said it helps solve a logical problem …
That’s a good tip. If you want to get really clever you can also position the spacers such that they hide the tops of all of the side arms. But now it’s quite the spacing puzzle as you have 6 location constrained spacers (bow, stern, oars and 3 sidearms)
Don’t forget if building a GIS to put in the frame head screws. There are only 6 screws in the hull – and they are in important positions as crack and split stoppers.
Here is a link to the Facebook discussion on this topic. Join the group if you want to see more tips.