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Ben Miller

Catspaw 8 #799

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Hey everyone! I'm getting started on a Catspaw 8. So far everything is going pretty smoothly, but a couple of questions have come up about the transoms and I thought I'd throw them out here on the forum.

 

I've glued the stiffeners to the transoms, and I'm at the point where I need to bevel the port and starboard ends of the stiffeners to match the angle of the sides. My question: Should I also bevel the edge of the plywood, so that the stiffener and the plywood edge make one continuous plane? Or do I bevel just the stiffener, so that the side will contact the beveled stiffener and then the outboard corner of the plywood, with a little triangular gap in between the two?

 

Second, I'm having a little trouble deciphering the plan diagrams that show the framing for the stern seat. My interpretation is that the 1 1/2" x 3/4" piece of seat framing that attaches to the stern transom goes below the transom stiffener (i.e. so it's attached to the plywood, not the stiffener). Then it has a shallow U-shaped notch cut in it so that can overlap the filler piece and the outboard pad. That was hard to explain, and probably hard to understand, but does it sound like I'm on the right track?

 

Thanks for the advice!

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Hi Ben,

 

You do not need to bevel the ply. We prefer leaving that gap so that it will fill with epoxy when you lay in your fillet. The bevel for cutting the stiffeners can be taken from the quarter knees. Most people do not even bother with beveling the stiffeners just filling the gap with thickened epoxy. I like to bevel them but if you get it wrong and have too much bevel you will have to trim it off which can be difficult because it is across the grain. I find that a mini grinder with a sanding disc will allow you to trim it easily. On the same note; when you screw the sides to the transom stiffener, you need to just draw in the screw until the sides just touch the transom. If you tighten the screw it will pull in a fish tail when viewed from above.

 

I need to look at that plan to be sure that I give correct advise because there have been some options, the way I intended it was as you interpreted it. The 1 x 2 should be fitted round the vertical reinforcing. Because the transom rakes, you need to bevel the top edge of the 1 x 2 so that the ply top will sit flat.

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Thanks! Not beveling the plywood will definitely save some work, and I feel up to beveling the stiffener at the appropriate angle.

 

Sounds like I'm good to go on the 1 x 2 seat framing. Off to the next step!

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10 hours ago, Designer said:

The bevel for cutting the stiffeners can be taken from the quarter knees.

I thought I was all set, but this line threw in a new complication. The specified angle for the stern stiffener matches up perfectly with the aft quarter knee, but the forward one does not. Which one should I follow?

IMG_3480.jpeg

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Ben, 

The angle between the sheer and the top of the bow transom is approximately 115 deg. That would be the angle of the forward quarter knee (or very close to it). The bevel angle of the stiffener on the bow transom will not be this angle because the bow transom has a lot of rake compared to the stern transom. Measuring the angle at 90 degrees to where the side and bow transom come together (shown with a disk below) is much closer to the given angle of 127 deg. I can see how that would be confusing but that is the angle you would set your bevel gauge to in order to cut a bevel on the end of the bow transom stiffener.  Let me know if that make sense. 

-Alan

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  • Thanks 1

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It took me a couple of reads to get it, but yeah, that does make sense. Thanks for the explanation and the illustrations.

 

Boat geometry is hard! I'm glad you guys figured it out for me. 👍

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Overthinking things again on a weekend morning...The plans don't call for sheathing the hull in glass. If the plans don't call for it, then I'm sure it's not necessary, but I see that some other people have chosen to do it anyways (one example). What are the pros/cons of doing it vs. not doing it?

 

I'm going to be using this to row out to my boat on its mooring. It'll get stored on dry land, so there'll be a little bit of hauling it in and out of the water, but no really rough treatment.

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Correct, not necessary for strength. If you want the lightest boat possible then don't sheath in glass just tape the seams. Every ounce counts on a small tender. It'll make it easier to carry and haul on board. That is what I personally would do. On a small boat it's easy to do little repairs to the bottom if it gets scratched or dinged. You can just flip it over, do the repair and your good to go. 

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Thanks Alan. That helps. After a week working on the transom framing it's coming together into the shape of a boat. Yes, I can get it out of the room. 😁 I know that because we stitched it up outside and then carried it inside to do the tack-welds.

IMG_3493.jpeg

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