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Petrel play SG: Rounding the chines, how much?
In the manual it says to plane the hull chines with a hand plane, creating a 1/4" flat, then round over with sandpaper. It says nothing about exposing the epoxy fillet.
The beveled panels only make contact with each other at the outside of the boat, not across the entire bevel. (i.e. the angle is open on the inside of the boat, which gets filled by epoxy fillets).
So this leaves only about 1mm of actual wood (the face veneer) on the outside that could be removed before you would hit the epoxy.
How much round over is required?
Is it the designer's intention to expose the epoxy, creating a stripe at all the chines? That stripe would then fade to nothing at the bow & stern where the panels butt together without the bevel.
I have rounded mine over with just sandpaper so far and the fit up is great, appearing almost seamless over most of the boat. Im hesitant to go further and risk exposing epoxy....and of course I dont want air pockets under my fiberglass from sharp edges either.
4 replies:
RE: Petrel play SG: Rounding the chines, how much?
The goal of rounding the chines is to get the fiberglass to make the corner without lifting away from the wood. The radius can be small, but the effort to get the glass to lie flat is more difficult. Entirely up to you.
If the glass lifts off the wood there are several ways of correcting that. See other posts about air bubbles in the glass.
On my Shearwater 17 I just hand sanded a small radius (maybe 1/8") and none of the woodflower fillet was exposed, The fiberglass made the turn just fine.
Then on the deck to side joint, I made a bigger radius. Maybe 1/4" or 3/8". I felt it would be nicer ( for paddling not to have a hard corner there) and the turn for the glass in some places was more than 270 degrees. A small stripe of the fillet was exposed, especially in the center of the boat. Maybe 1/16" wide. Looks OK. You really need to look for it with alll the beauty of the grain going on. In fact I need to go look at the baot to see what happened because I did not even notice. Certainly no one beside me, and you, will ever notice it or even know what it is.
Hope this helps, have fun,
Joel
RE: Petrel play SG: Rounding the chines, how much?
I did not round over that much. I just took enough of the "points" off so that the glass would lay flat.
RE: Petrel play SG: Rounding the chines, how much?
Before electing to build the Petrel SG (17), I had a chance to paddle the strip-built version and was blown away but it's handling characteristics. Since it's not possible to get to the same refined hull shape with the SG version, I contacted Nick for feedback on its handling, with my feedback on the strip boat as context. His response was essentially 'have at it' when rounding the stems. You'd have to go pretty deep to mess up and even if you expose the epoxy fillet, the boat's strength will remain intact.
RE: Petrel play SG: Rounding the chines, how much?
» Submitted by APD_NY - Mon, 8/22/16 » 10:39 AM
....The end of my post got cut off....
I dont want to expose the epoxy if not necessary, but if I have to for good FG lay up, then I would. All the pics Ive found online dont appear to have a contrasting stripe, making me think that less than 1/4" is OK, but there are no real close ups of the chines. I did not stain my hull panels, so the epoxy will appear as dark stripe against the lighter okume.