20250630

Experimental Oars for Hatseflats

Why new oars?

After 7 years of hard use my trusty Lahnakoski oars squeaked alarmingly with every stroke. My friend Joost said that the oarlocks were crying for lubrication. Alas, too late. There was already so much play between the oarlocks and their sockets that I had to replace them. I asked for a new set of bronze oarlocks and sockets at the Bootbouwer but the bronze oar locks for the Lahnakoski oars were not available anymore. What to do?

Joost had a spare set of sockets and square oar locks that I could use. The sockets were identical to the old ones so fitting them to the gunwales was a piece of cake. The old oarlocks still fitted the new oarlocks but with some play. So I had to use them carefully and lubricate them every time with leather grease.
The other part of the solution was to create some new oars to fit the square oarlocks. That sounded like a lot of work. And that it was!

Experimental oars

The easiest solution would have been to repurpose some carbon racing oars for Hatseflats. These already have collars for square oar locks. However, I am not a great fan of carbon fibre on small boats. You have to treat them really carefully and when they get damaged you end up with the worst possible splinters cutting your flesh.

Joost likes carbon, but indicated that carbon is not so suitable for small and slow boats (sorry Hatseflats). Because small cruising dinghies don't plane and need to have some volume to stow all that gear, the extra pull from carbon oars simply goes to waste. In order to row comfortably (at a slightly lower pace) you even want the oars to be a little more flexible than my Lahnakoski oars.

In 2018 Joost had created plans to build oars for the Goat Island Skiff which would be a good starting point for Hatseflats. The benefits of these oars were: slightly more flexible looms for more comfort and spoon blades for rowing with less effort. Since these plans had been used for years there was nothing experimental about this approach, you would say.

But here is the twist: the plans from Joost required laminating the oar blades from two or three layers of 3mm veneer, The experimental approach suggested by Joost was to make brutally simple blades from 4mm plywood, reinforced with 200g glass cloth on the hollow side and a simple rib on the backside. Since the spoon blades had a very tight curve halfway the length of the blade, there would be no need for elaborately carved looms to receive the spoon blades, like in the plans. Instead, a simple straight taper on the last foot of the loom would suffice to fit the blades on the looms.

More experiments

I started by creating new blades using an earlier experiment by Joost as a reference. With a length of 60cm and a width of 13cm my blades were going to be only slightly wider than my existing Lahnakoski oars. I did not need extra power but more comfort: I hoped that the spoon shape would mean less strokes and that the narrow blades would be comfortable in waves.

Joost and I discussed the shaping of the looms, the end of which was that I would use the online drawings of the oars that Joost had made for the Goat Island Skiff. I used the building notes created by Joost to understand the building process and consulted the drawing for the correct dimensions. Only a couple of changes were required:

• keep the section of the looms square until after the collars.
• add a straight taper to the last 30cm of the loom to accept the experimental blades.

Dimensions

Unaware that I was not using the correct drawing, I came up with the following dimensions:

• blade: 610x132mm - see photo for more measurements
• loom dimensions: 44x44mm
• handles: 34mm x 180mm
• untapered length: 950mm including 180mm handles
• tapered length: 1460mm
• vertical taper: straight taper top and bottom from 44mm to 30mm
• horizontal taper on outside of loom: none
• horizontal taper on inside of loom (to which the blades are attached): straight taper from 44mm to 30mm

Building the blades

• Created a 600mmx132mm blank out of 8mm plywood
• Created 4mm blade using the blank
• Cut 2 27x4mm ribs from solid pine with 100mm extra length
• Created a jig to bend the blade and ribs with a sharp bend at 280mm from the pointed tip
• Glued ribs together with blade into the jig and fixated the blade with screws etc.
• Sanded the backsides of the blades
• Added 280g glass cloth and epoxy on the hollow side of the blades
• Coated the hollow side of the blades for a second time to ensure that total permeation of the glass cloth

Building the looms

• I laminated two 2700x44x44mm oregon pine looms from two staves of 44x22mm each.
• I used a router to locally reduce the looms to 34x34mm for the handles. With the router I cut 5mm notches across the last 180mm of the looms. After cuttting out the notches on all four sides of the loom, I chiseled out the remaining ridges.
• I then used a surform to convert the square handles into octagonal handles. And rounded them with 60grit sanding paper.
• After shaping the handles, I cut the looms to 2410mm.
• I marked the vertical tapers starting from 950mm from the tip (including handle).
• Planed vertical tapers by hand (No 3 plane).
• Marked horizontal taper on the inside of the loom and planed by hand.
• Created straight taper for the last 280mm of the inside of the loom to accept the blade.
• Rounded the corners with the router and a 15mm bit.

Assembling looms and blades

• Marked out 280mm on the blade. This is the straight bit just before the bend.
• Glued the straight part of the blades to the tapered ends of the looms.
• Planed the sides of the ribs and looms to fit.

Finishing work

• Sanded excess epoxy from blades and ribs
• Coated hollow sides of the blades with epoxy for a third time.
• Coated backsides of the blades and ribs with epoxy
• Coated backsides of the blades and ribs with epoxy for a second time.
• Coated backsides of the blades and ribs with epoxy for a third time.

Next steps

At this very moment, there is not much more to do. The epoxy needs to cure for 14 days before it can be painted over, so I wait.

After these two weeks I will coat the new oars with a one-pot transparant paint of Epifanes. Not epoxy or two-pot polyurethane. The oars are expected to flex a little bit so we need a slightly elastic surface finish. A hard surface finish of epoxy or two-pot polyurethane might crack in the long term. We don't want that, so bring on the varnish!

I will treat the bare wood with three coats diluted with 20-30 percent solvent so that enough paint is soaked up by the wood. Then I will add three more coats of undiluted paint to the oars including the blades which are now coated in epoxy.
I am looking forward to the end result, a few weeks from now!