2015-06-24

Post XXXIII - Keel Fiberglassing, Oarlocks & Fitted Gunwales

Before I get into more glue spreading, here are a couple of pictures of the fully mocked-up gunwales, without scuppers on the inner wales. Figs 147 and 148 illustrate the twist I had to put in the inner wale in order to get it flush with the breasthook. Looks pretty damn cool with the structural pieces added on, and I was sad when I had to remove them (remember, they are going to be glued and screwed in the end).


Figure 147: Fitted gunwales, breasthook and knees. 


Figure 148: Somebody will probably tell me this is wrong, but I like the screw heads to be showing.


Oarlocks, as it turns out, are not a straightforward boat part. They used to come in all shapes and sizes to fit dozens of applications and rowing needs. Today, much-reduced demand for metal oarlocks has caused many foundries to stop producing them. Pete Culler's book "Boats, Oars and Rowing" laments this at length.

From my various readings, I decided I wanted the typical symmetric open-top oarlocks. This is not a performance boat and I don't want to get into all the carryings-on about blade angles and shit that the competitive rowers deal with. Closed-top oarlocks are a massive pain in the ass too -- so they were out. I wanted a tapered shaft if at all possible. The tapered shaft is supposed to be less noisy and clunky-aroundey as it wears. Last, I didn't want plastic, and didn't want to pay 40 bucks a pair + shipping just to have fancy bronze ones.

First thing I found: there is no such thing as a tapered-shaft bronze oarlock unless you custom-order. Second, almost all oarlocks are bronze/brass or plastic and are terribly expensive. After exhaustive seaching on the web, I came across Mercer Marine in Clarenville NF, Canada. They carry a tapered galvanized cast-steel oarlock and socket. They are cheap, extremely tough, and shipping is not too bad. I wanted side-mount sockets because I know the top-mount sockets for these locks are way too wide for the inwales of my boat. Not too big of a deal to change it later if I decide I don't like it.

Figure 149: Galvanized Tapered locks and sockets - Mercer Marine in Newfoundland.


With the gunwales removed, I started prepping the hull-transom joint and the keel. Both of these do not strictly need reinforcement with FG, but both areas are high-wear and I thought it best to add a bit of the good-stuff over top. Preparation is pretty simple; it's the same for cured epoxy where you want to add another layer. Simply scuff sand the area that will be receiving the new glass layer, clean away the dust and wipe with isopropyl acohol. I had taken the opportunity a few nights prior to fill all of the remaining screw holes in the keel with thickened epoxy. 

Figure 150: Prepped transom-hull joint.


Figure 151: Just showing off now. Nice straight keel. Prepped for fiberglass. 


Fiberglassing around corners:

This is difficult at the best of times. If you are going to do a regular-bias cloth strip then the corner (inside or out) must have a radius. The size of the radius will depend on the weight of cloth you're using and the orientation of the cloth fibers as they round the corner. Consequences of not adding a radius can be pretty dire -- it usually means that the cloth will peel itself away from the wood underneath and create a massive air bubble when the epoxy cures. This is bad as it is hard to hide, tough to sand out, and is not as strong as FG that is stuck right to the wood.

Luckily, you can cheat the system a bit using a diagonal bias strip. These aren't something you can buy, but you can slice it out of a sheet of regular-bias cloth. The diagonal fibers attack the corner at a 45 degree angle and do not need to bend near as much to round it. Diagonal-bias cloth readily expands and contracts, and does not need to do so uniformly. It's advantageous for a complex curve like the transom-hull joint where there is a transition from a convex to a concave curve over a short distance.

Even using the diagonal bias however, my 10oz cloth was a bit too stiff to round the corner and I got a few air bubbles. They were not large and were fixed after curing by injecting some extra resin beneath the weave using a needle and syringe (purchased from the local farm-store).

Figure 152: Diagonal-bias FG strips to round the sharp corner. 


Figure 153: Carrying the strips right up the sternpost and overlapping.


The keel was prepped using the exact same procedure: scuff-sand, remove dust and wipe with alcohol. Here, I wanted to use a scrap full-length piece of 10oz cloth rather than piecemealing a bunch of diagonal-bias strips. Knowing that this will not turn a tight corner, I added a significant radius on the outer edge of the keel and a good-sized fillet where keel meets hull. This fillet was needed anyway to clean up the piss-poor job I did at filleting the first time around.

Figure 154: Prepping the keel and hull to receive a glass strip. 


Figure 155: Glass in place -- first layer. To be given a fill-coat later.


For both of these parts, I came back before the first layer had completely cured and added fill coats to bury the weave. This is important since it's all external and rough surfaces create more drag. That's the last thing you want in a man-powered boat!

This also about finishes the building work on the outer hull also. All that's left now is to do a final sand and apply paint!!! I'm not looking forward to yet-another sanding escapade, but it will be good to finally have it ready for the water.

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