Drawing out the next major Zip part

At first glance, the Zip has some rather odd frame designations.... Specifically, frame number "5-1/2".

It seems odd until you understand that the designations are logically based on boat design drawings. If you look at a cross-section drawing of the boat, there are several vertical lines that divide the hull into sub-sections. Each one of these vertical lines is called a "station." The numbering starts at zero (the transom), and ends at "F.P." (which stands for "Forward Perpendicular") at the foremost tip of the boat. In the case of the Zip, there are 8 stations including "F.P.", dividing the hull into 7 sub-sections of about 24-1/2" each. Frame # "5-1/2" is the frame placed between stations 5 and 6. It is located near the base of the stem.

Frame number 5-1/2 is a very important part. As the instructions indicate, the horizontal line formed by the floor member of frame # 5-1/2 is the plane from which the rest of the boat is set up. The instructions specifically state to take extra care to ensure that this part is accurately measured and constructed.

I just finished drawing this part, and I thought it would make a good blog post to illustrate how the Glen-L plans are copied to the wood.

First of all, you fold the carbon paper in half, so that the lines you trace through it are transferred to both the wood AND the back of the actual plans. Then you place the plans on the wood, and flatten them down securely. Push pins help for this.

Secondly, trace the plans for the part you want to build. As I mentioned in an earlier post, the centerline is THE crucial reference point for the boat. ALWAYS carefully draw the centerline. Make sure you extend your traced centerline beyond the needed dimensions of the part, for this reason:

Third, draw "sight holes" that are centered on the extended part of the traced centerline. I like to trace a small coin for this purpose. Use an exacto knife to cut your sight holes through the paper. Youll need these holes to align the plans after you flip them over.

Here Ive traced out the floor timber, and have cut sight holes on the centerline.

Next, remove your push pins, plans, and carbon paper from the wood. The half-width of your part should be clearly visible.

Half-width of the floor timber drawn onto 3/4" Douglas Fir marine plywood.

Now, un-fold the carbon paper, and place it normally onto the wood where the second half of your part is to be drawn. Flip the plans over, and youll see the carbon-copy you made on the back of the plans. Carefully and accurately align the sight holes on the extended centerline that is traced onto the wood. Again flatten the paper down securely. Now youre ready to trace the second half.

Plans flipped & aligned. Ready to draw the second half of the floor timber.

Trace the carbon-copied lines onto the wood, just like you did the first side. When youre done, the full part will be drawn onto the wood.

The full floor timber drawn onto the wood, waiting to be cut out.

Read More..

Fitting the Utility’s port side planking — and a little more progress on the Zip

Having previously used the starboard side planking as a template to draw and cut the port side, fitting the port side planking was relatively quick and simple. Busy days full of other obligations have meant that I’ve had to work on the boat incrementally... 20 minutes here, 45 minutes there... but, its getting done.

Thanks to a little help from my daughter, I’m now most of the way through driving the screws to hold the planking down. The new DeWalt titanium drill bits I bought have been a real pleasure to work with, particularly since my older ones had become almost too dull to use.

Dry-fitting the forward port side planking.

February brought with it an unusual amount of snow this year. In addition to school cancellations, there were a few days when I got snowed-in at home. I took advantage of these days to draw out the construction drawings for my Zip on a big sheet of eucaboard.  I drew the frames out as they would overlap one another, based on their shared x,y axis & set-up level. This will be a great reference for checking  the frame parts for accurate shape & for assembling the frames. It is also a very useful tool for checking the relative dimensions of various aspects of the hull.

My Zip construction drawing on a big sheet of eucaboard.

Last Christmas, I received a copy of How to Fiberglass Boats, by Ken Hankinson, along with the accompanying DVD. I finished reading it recently, and I’ve enjoyed watching the DVD. It’s useful information for those, like me, with minimal experience at working with fiberglass. It takes a lot of the mystery out of the process, and its very helpful to watch someone else actually doing it. 

Additionally, the book is very enlightening about precautions to take when working with epoxy.

With any luck, Ill be able to fiberglass the Utility’s hull before summer.

Read More..

Epoxy work on seats sheer and Zip parts

The last post left off with my having cut out a piece of Meranti for the rear seat. This weekend, I laminated that onto the A/C exterior plywood... and did a little more epoxy work along the way.

1/4" Meranti top for the rear seat

Just as Id done with the front thwart, I coated both mating sides with epoxy (not thickened), and held them together with concrete blocks and weights while the epoxy cured. I had just enough epoxy left over to also add a 2nd layer to the Zip transom knee.

Laminating the Meranti onto the rear thwart. I used the extraneous epoxy to encapsulate the underside of the front thwart, as well as the transom knee for the Zip.

Regrettably, however... after the epoxy cured, there remained a small gap.

And a dust bunny got stuck in the epoxy on the Zip part.

All this didnt go perfectly according to plan. After the epoxy had cured, I found a gap between the two layers that would need to be filled. Also, some dust had gotten stuck in the epoxy on the Zip transom knee. I am trying for substantially better fit and finish on the Zip, so I sanded off the dust bunny & planned to encapsulate with a third layer.

Logistically, I thought it best to encapsulate the undersides of both seats next. This would be the 2nd coat for the forward thwart. I planned to tilt the rear thwart just a little so that epoxy would run into the gap and fill it. Since I havent trimmed the Meranti top yet, this should help the epoxy flow down into the gap. With the extraneous epoxy, I planned to encapsulate the underside of the sheers on the aft third of the boat, as well as the Zip part.

I ended up having more left over epoxy than expected. So after quickly cleaning them off, I also encapsulated part of the Zip stem and the forward face of frame 5-1/2.

More encapsulation; trying to fill the gap on the aft thwart. Here it is propped up slightly with a scrap of mahogany left over from the quarter knees.

Epoxy drying on the Zip stem & frame 5-1/2.

Current Status of Zip Parts
Part	Status
Stem & Breasthook Assembly	Most surfaces have 1 coat of epoxy
Frame 5-1/2	Forward face has 2 layers of epoxy. Other surfaces have 1 layer.
Frame 4	Side members cut, but have not been planed or notched for sheer.
Transom Knee	Coated with 3 layers of epoxy
Transom	Side frame members cut 1/4" oversized on outer side. Have not been planed.

Read More..

The Zip takes one step closer to reality

Last night, I assembled the breasthook and stem assembly for my Glen-L Zip. From my previous experience of having built stems and breasthooks for two other boats, I decided to use a different technique this time.

In the past, I would assemble the two pieces of the breasthook and let the epoxy cure. Then, later on, I would attach the completed breasthook to the stem. This time, I assembled all three pieces together at the same time, using only one batch of epoxy.

The reason for doing it this way was to avoid having to deal with the bead of hardened epoxy that forms along seams where the epoxy is squeezed out from between two parts. I’ve learned that it’s a good idea to scrape away any squeezed-out epoxy before it cures by using a small, flexible putty knife. Still, if a bead of hardened epoxy forms on an inside corner, (such as in the notch of the breasthook), it can be difficult to remove. It can also cause problems when you’re fitting pieces together.

By putting all three pieces together at the same time, this problem is easily avoided. 

I decided to assemble the breasthook and stem with the same batch of SilverTip epoxy that I was using to encapsulate limbers and underside parts on the Utility. Not much epoxy was required for this small bit of encapsulation. I had a small amount of #2 silica ready to add to the remaining epoxy when I was done. The Zip parts were disassembled and staged, ready and waiting for the epoxy.

Limbers & underside parts of the Utility needed to be encapsulated before I attach the bottom planking. I wont be able to reach these places once the planking is on.

All the Zip parts set to go: stem, mixing cup for epoxy, kitchen scale in a freezer bag, chip brush, screwdriver, putty knife, awl, small container for #2 silica, mixing stick, rag, and both parts of the breasthook.

After encapsulating some small areas on the Utility, I mixed the silica with the remaining epoxy to thicken it for gluing. I spread this mixture on both mating surfaces of the breasthook and on the top of the stem as well. I used an awl to quickly align the holes on the two parts of the breasthook, and screwed them back together. Then, I fitted the breasthook onto the stem, pressed it down firmly, and used two 2.5-pound weights to hold it down into position. Then I scraped away all the epoxy squeeze-out with the putty knife.

The Zips stem

Stem and breasthook assembled, waiting for the epoxy to cure. These parts are all made from 3/4" marine-grade Douglas Fir plywood.

Read More..

Working on the Zip

This blog started off with a reference to the Zip plans I had just ordered back in April. The plans arrived a week after I made that first post, and I got started on the stem that very weekend.

During breaks while working on the Utility, I have slowly & purposefully been working on parts for the Zip. I have been taking my time, carefully shaping the parts. Im in no rush at this point, since after all I still have the first boat to finish.

Ive made it a point to cut just outside the lines on the parts so far, then sand them down to the line. So far Ive got the stem shaped, as well as the lower piece of the breasthook. I cut the top piece of the breasthook earlier today. Not much to show so far, but here are some photos.

Tracing the stem onto 3/4" Douglas Fir marine plywood.

First stem piece cut. Using it as a template to trace out the second piece.

Carefully filing out the notch in the lower breasthook piece.

The shaped Zip stem needs to be epoxied. Construction on the Utility is underway in the background.

Read More..

Zip stem construction

Todays blog post is about assembling the stem for my Glen-L Zip. The Zips stem, as with many Glen-L designs, is made from two identically shaped pieces of 3/4" marine-grade plywood, laminated together with marine epoxy and fastened with silicon bronze screws.

This is now the third stem Ive built; the other two being for a Squirt and a Utility. Learning from previous experience, I did a few things differently this time.

First, I spent much more time and care in shaping the pieces beforehand. I feel very comfortable this time around with the shape being correct.

Second, I used less epoxy. The other two times, I globbed a bunch of thickened epoxy on, just to make certain there was enough. In reality, that just creates more of a mess, because the majority of it squeezes out.

Third, I kept a putty knife ready to scrape away the epoxy that squeezed out from between the two layers of plywood. This makes for much less sanding afterwards.

Also, having learned a tip from a fellow boatbuilder, I used an awl to quickly align the pre-drilled holes before driving the screws back in. This proved to be a great time-saver, since it can be a little tricky to mate the holes back together with epoxy spread over the wood, (particularly while wearing latex gloves, goggles, and a respirator).

For the epoxy, I used Glen-L Poxy Shield, thickened slightly with #2 silica. Poxy-shield is mixed in a 5:1 ratio, using 5 parts resin to 1 part hardener. It can be hard to find very small mixing cups in order to measure small batches of epoxy, so Ive used my own method. I take a regular off-the-shelf mixing cup, and measure the distance between the pre-printed volume marks. So far, all the cups Ive used had a distance of 8mm between the 4oz and 8oz markings. So, I add marks every 2mm between them to show the 5oz, 6oz and 7oz lines. That way, I can pour in 5oz of resin, then add hardener until the mixture reaches the 6oz line. There are, no doubt, more accurate ways to go about this. However, this way is quick, simple, cheap, and effective.

Perhaps not the most scientific method, but it works.

After mixing and thickening the epoxy, I spread it out on the mating surfaces of each stem piece, making sure the whole area was covered. Then, I put the pieces together & aligned a couple of holes with the awl. I dipped the silicon bronze screws in a little epoxy, then drove them down into the holes. Then, I clamped the pieces together solidly, driving the screws in further as needed. Afterwards, I scraped away the epoxy that had squeezed out from between the layers before the epoxy became unworkable. Then I left it alone to let the epoxy cure overnight.

Everything ready to go: Stem parts, Poxy-Shield resin and hardener, #2 silica, mixing cups, mixing stick, chip brush, awl, screwdriver, extra screws (just in case), clamps, and putty knife.

Glued, screwed, clamped and scraped with the epoxy curing.

On a final note, I also worked on the Utility over the weekend... still fairing. It seems like a never-ending process, but its getting there.

Read More..