Cutting Molds In Relation To Sheer Line

[Steve Oostema]

Hello All,

I am new to the forum and also in the process of building my first strip canoe. I have a question regarding where to cut my molds in relation to the sheer line. When cutting out the molds, would you cut them at the sheer line leaving an edge for the bottom of the first sheer strip (obviously not cutting all the way from port to starboard as you want a section of the mold to attach to the strongback)? Or do you cut the molds a little past the sheer line (closer to the strongback) and just mark the location of the sheer for the installation of the first strip?


Thanks for your help,
Steve

 

[Rod Tait (Orca Boats)]

I am assuming you are building a cedar strip/fiberglass canoe? It helps to have a little extra material below the sheer lines on the forms. What plans are you building from?

 

[Steve Oostema]

Thanks Rod. Yes, I'm going to be building a cedar strip/fiberglass canoe. I'm lofting the Ranger plans from Canoecraft.

 

[Mike Daugherty]

I am currently making the Ranger as well. I have the molds mounted on the strongback. I lofted my molds from the Canoecraft book was well. I created a 1” area below the sheer line in anticipation of trying the stapleless method and needing somewhere to place the bottom jig. In effect I dropped a line straight down from where the curve of the mold meets the sheer line and extended it down 1”. From there I cut the base back to 6” from the centerline. This way the part of the form that rests on the strongback is 12” wide and fits the top of my strongback. BTW I aligned my molds on the strongback using a cheap laser level. One of those levels with the built in laser that can do a dot or a line. I did use the string method to align the bow and stern assemblies first. Then mounted the laser on the bow and a target on the stern.

 

[Mike Daugherty]

Every time I think I can progress I find something else. So while holding a plank up to the mold to check for “fairness” I ran into an anomaly. While touching Station o, Station 1, and station 2, everything is good. When the plank is then touched to Station 3, a gap forms at Station 1. I am sure it could be forced to touch but is this normal?

 

[garypete]

You'll be able to avoid this problem if you use the stripping format shown in Canoecraft. Rather than putting the first strip at the sheer line, Ted Moores sets the first strip about 4" down from the sheer, letting the strip bend naturally at each end. He then strips up and down from the initial strip. This makes a much nicer looking canoe than one where all the strips are parallel to the sheer.

If you use this technique, you'll need longer forms for the first 3-4 sections at each end, so the forms should not be cut.

. See Canoecraft for a visual explanation.

I just built a Prospector from the book and the Bear Mountain Boats plans came with an accurate drawing of the canoe as seen from the side. The plans are 1-8 so I enlarged the side plan 800% at Office Max, cut out the shape and taped it onto the finished hull. From there, I cut the sheer using the taped-on pattern. Worked perfectly.

 

[Dan Lindberg]

This of course assumes one likes the look of straight strips.

This makes a much nicer looking canoe than one where all the strips are parallel to the sheer.

 

[Mike Daugherty]

Interesting. My copy of Canoecraft talks about letting the first strip follow the waterline somewhat. It never talks about starting 4” down from the sheer. Oh well. Doesn’t matter. My molds are set. I will mount my first strip at the sheer at station 0, but will not force it to follow the sheer at the other stations.

 

[garypete]

You'll like the finished look of the boat better than if you had followed the sheer completely with the first strip. Especially if a canoe has high ends, having all the curving strips parallel to the sheer looks amateurish to me.

Here's a picture of my latest canoe where we essentially stripped it the way you are planning to do.

If you follow Canoecraft's methods, you'll end up with a fine looking craft..