Monday, July 3, 2017

Revisiting the stem

Work has slowed considerably on the Zip. There are a couple of reasons for that:

The first and best reason is that I finally have a completed boat to play with. Now that the weather is warmer, I'd simply rather spend my time out on the lake in the Utility than cooped up in the garage working on the Zip.

The other reason basically comes down to planning. Every little piece and component is interconnected on a boat. For example, the shape of the dash beam depends on the layout of the gauges and switches. The layout depends on what gauges and switches I want to use.

Then, comes the question of a motor. 

If I get a 40 or 50 horsepower motor for this boat, my budget will basically demand a used 2-stroke motor. Here's the problem with that: I'd prefer not to use an old 2-stroke motor. Call it my inner tree-hugger. I'd rather have a cleaner-operating Evinrude E-TEC or a 4-stroke motor. And, you guessed it... those are just too expensive.

If I get a new motor, then my budget basically limits me to 20 or 25 hp. So, it's a matter of compromising either emissions, or power. For a lot of people, that's a no-brainer. Prioritize power. I get that. I do. 

However, power and speed isn't all that important to me. On the other hand, I don't want to invest all this time and work to wind up with an under-performing boat, either. So, if I opt for a 20–25hp motor, that decision will affect the length of the boat. The shorter "version" of the Glen-L Zip is called the "Flying Saucer." It's designed at 12' 3" and has a maximum horsepower rating of 25. 

And so there you have it: progress has been stalled by having to make decisions (and/or purchases) regarding instrumentation and power. What to do in the meantime?

Why not work on the stem?

If you read much about either the Zip or the Flying Saucer, you'll find a lot of comments about the boats' tendency to be light in the bow. Most builders look for ways to shift some weight forward, in order to keep the bow down. A popular choice is to mount the fuel tank up front, and I'll probably do that.

But, I decided to also add some bulk to the stem. 

As-designed, the stem is 1-1/2" wide (2 laminations of 3/4" plywood). I added additional 1/4" pieces to the sides, increasing the width to 2 inches (which is also what I did with the transom knee). I had to leave a 1-1/2" channel for frame 5-1/2 to fit into, because I did not want to widen the notch in the frame.

Here, you can see the 2 additional layers of 1/4" plywood attached to sides of the stem, forward of frame #5-1/2.
This photo shows how frame #5-1/2 fits onto the stem.

Here, I have clamped a scrap piece of 1/4" plywood onto the side of the stem, aft of frame #5-1/2. This allowed me to simply trace the shape of the stem onto the new parts, making sure to leave enough of a "channel" for frame #5-1/2 to fit into, without widening its' notch (and weakening the frame unnecessarily).

As I worked on the stem, I noticed that the breasthook was not accurately perpendicular to the stem. So, I also added a tapered piece to the top of the breasthook to correct it. This should help when the frames are all on the building form, and it's time to mount the stem into place.

Something just didn't seem right about the breasthook. So, I put the whole assembly in my vice and made sure it was level laterally.

Then, I made sure the breasthook was level, linearly.

The moment of truth. Checking the breasthook laterally, it was clearly nowhere close to perpendicular to the stem.

I found that the breasthook "dropped" almost 5/8" from tip-to-tip.
To resolve the issue, I made a shim by laminating 3 pieces of 1/4" plywood together: One full-width piece, one half-width piece, and one quarter-width piece. I faired it with a belt sander and a finish sander.

The shim worked within reason, so I epoxied it into place.

1 comment:

  1. Nice fix on the breasthook Mike. As for the motor, consider that it is going to take some time to finish the boat. If you can, establish a weekly fund savings amount to gradually build up the funds needed for the motor. It will go slow at first and probably won't be all that you need to get the ETEC, but it will get you closer than no savings at all and reduce the amount you need to finance.