Final Alignment Help

[Glen M]

Went 3d on my 10N hull this weekend. All pieces fit right together, with exception of the forward bulkhead which needed some minor bottom sanding.

When all stitching was completed, it looked as if the hull was twisted. I put a straight edge on the bow and one on the stern gunwales and they were out of level. The hull could be easily twisted into shape to where the edges of the metal were lined up.

This being my first attempt at this I don't know the proper procedures for lining up the hull before I start welding the seams?

Thanks

[Brent]

Glen, I was hoping one of the xxN builders would chime in here. Lacking that...

You are right on to get the boat straight before welding the joints with epoxy. I let my boats settle in for a few days during the stitching process, allowing the wood to slowly move into the final location. In the forward third of that boat there probably some severe bending of ply going on. Several on this forum have reported cracked ply in the bow area of the Spindrifts...so go slow and careful.

The twist is no doubt the result of some type of forces, and my first guess would be to look in the forward third area of the boat. I bevel the ply edges to get better alignment of the pieces. If you are seeing gaps between the sections, that is a place to start analyzing the reasons.

[Tom Lathrop]

Glen,

Twist is always a concern with all S&G boat projects and it must be prevented at all points thoughout the building until all structural parts have been bonded. X-member battens from about the forward bulkhead to the transom can help control the shape and the boat should be supported in in transverse forms that help to hold it in allignment. I'm sure the plans say to put in all port and starboard symetrical components in pairs to avoid warping the hull also. This is especially true of rubrails.

[Steve Day]

Glen,

Both Scott and Tom have good advice. Look for uneven stresses that have been imposed on the plywood as you stitched her up. That is most likely where the twist was imposed. I had a little bit of that on mine as I was doing the initial stitching, but was able to work through it carefully as I drew the pieces together and ended up with a straight boat when I was through tensioning the stitches.

The big thing to remember is to take your time and get it right before you start to epoxy her together. A little extra time at this stage is VERY well spent.

I did end up with a bit of a dish in the bottom just forward of the nesting bulkheads and wish I had taken a little extra time there to get that dish out. It does not seem to affect the performance and you really can't see it unless you are looking for it, but I know it is there. However, it is symmetrical, so it doesn't make the boat want to veer off course.

I hope you are having as much fun as I am with the construction.

Steve

[Glen M]

Thanks for the help.

I dont feel that it is a structural issue though. With the seams stitched, if I lift up on the port stern corner, this side of the stern will stay raised up higher than the starboard side. Same if I lift up on the starboard stern corner, it will stay raised up higher than the port side. She does not want to force her way back into a certian position, and will stay where it was last set. The stern corners will also move slightly up and down if I twist the bow. I was wondering if there is a way to measure this, or some trick to the trade on squareing up the stern with the hull and bow, and if there are any other alignment issues that I am probably missing?

Thanks again

[Tom Williams]

I used my 4 foot level on my CS 17. It's in a cradle (on casters) which I shimed up about 1/2 inch on the starboard stern corner to best level everything. Having the hull level worked out well because I was able to use the level later on when framing the seats, etc.

Good luck. You're going to have a great time with the project.

Tom

[Steve Day]

Glen,

I made up a couple of cradles for the boat and set it in the cradles. I used a laser level to square things up as it tensioned the stitches. Sorry, I forgot to mention the laser in my other description.

Laser or bubble level makes no difference as long as the boat is square.

Once you get her square in the cradles, you're home free on that issue.

Steve

[Scott Dufour]

With my CS17 I used two plumb bobs hung from the ceiling and several winding sticks laid across the gunnels. I carefully measured from the bow to equal points on the gunnels to make sure the sticks were even. Sighting a distance from both front and back, the plum bobs pointed out any twist or variation horizontally, and the sticks did a great job showing the twists. I was able to twitch and tug the thing into great alignment. Cheap and simple. Here's a pic of the setup.

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