Boat Builder Central - Builder Forums

Hello, can you please help me. I have finished the jig for my cs 23 but the bottom (keel) is not straight. I have a 20mm curve inwards, is that correct? you can see that in the photos

No!!!

No no no. Do not build that.

That is called hook and the boat will not perform properly.

Something is amiss.

Erich, See response from Jacques below:

"It is not correct, that keel must be straight. If there is any curve, it should be max. 10 mm convex, not concave.
Could it be that the transom thickness is taken on the wrong side? Will it be straight if you lower the transom?

Jacques will now see your Forum post and continue to assist you with identifying the issue.

Jeff

One thing I see is the transom angle cannot drop off. The transom bevel must be bottomed at the highest edge upside down. This would cause even more hook than you show.

I am not a ply builder, but I can tell you that you need to stop. Things are wrong.

Please wait for Mertens to reply.

I advise for now you describe in detail how your midship frame depths are so low and which frames are low.

Also, explain how you lined up the transom.

thanks for the answer i got the bottom line (BL) with a laser correct straight is that correct? my dimensions are correct maybe the plan is incorrect?

I really like using lasers Erich for setting up.

Yes. It costs about $100-$150 for a decent self leveling laser, but you drill a hole through the lines and you can really see errors easily.

For the larger builds; I find them super handy for establishing waterlines for painting and mine gets used often.

You need a tripod as well. Mine is a tacklife and I see they have one for like $40. Plus a $30 tripod and for $70 you can shoot lines through your layout.

You drill a small hole like 3/16" on your centerline at baselines or dwl and you can see if things are off.

Check all your measurements but whatever happens, that keel line should be straight.
Sometimes I design a small hog in it (concave) to make up for the thickness of the extra glass layers at the transom but never a hook.

erich.resch@gmx.at wrote: ↑Wed Sep 02, 2020 10:06 am thanks for the answer i got the bottom line (BL) with a laser correct straight is that correct? my dimensions are correct maybe the plan is incorrect?

BL is baseline I believe.

How can you shoot a laser through the transom?

The transom bevel is probably part of your error. Remember the angle of the transom. The BL dimension on the transom is different. If you take a piece of plywood and tip it 12 degrees it gets longer on one edge and shorter on the other.

The transom bevel is sin 12 degrees times thickness of 1.5" or 0.312" or about 8 mm..

If the entire setup was okay and you spotted the transom wrong; you'd get 8mm of hook.