Clipper's Vera Cruise Build

Clipper's Vera Cruise Build

Sunday, January 31, 2016

Spray Rails - Part 2

A stretch of very nice weather with temps in the mid 70's (even low 80's) this last week and weekend has allowed me to  make some more progress on the spray rails. The first order of business was to get the port rail extended and fitted up against that side of the boat. I wanted to insure that I could install both rails and have them line up at the front, and still look correct as they travel aft.

During the early part of the week, I kept trying to visualize on paper, how the tapers would look on the forward section. I wasn't having much luck with this. But with the starboard side temporarily mounted and the side taper drawn and taped off, I realized that the the thickness taper needed to be performed first regardless. I also decided that for now, I would not taper the top edge in the aft and middle sections because the transition to the tapered front would look strange.

For the thickness taper, I needed to determine how far aft I wanted it to start. This worked out to seven feet and was mostly due to the curve of the hull. The plan was to thickness taper the two laminations at the same time in order to get the angle to blend in nicely. This required alignment marks at the back end of the rail.

It also required that I insure that I had enough length on the second lamination in order to have the start of that lamination's taper have material to cut. I laid the second lamination on top of the first one and worked out the amount of taper increase from the front end. Using this amount of increase, I worked out how much length the second lamination needed in order to have material to cut.

This probably sounds confusing, it was to me. But basically the thickness tapers from 3/8" to 1 " over 7 feet. Somewhere along that seven feet the taper crosses the 1/2" thick portion of the rail. The second lamination needed to be at least that long in order to have the taper transition properly.

I pondered several different ways to cut the thickness taper, but in the end I decided on a modification of the scarfing approach I used elsewhere on the boat. With previous scarfing efforts I had precisely measured and cut two angles as determined by the ratio required of the scarf joint. Depending upon the thickness of the material this varies. Then I placed the material to scarf between the two angles and cut the scarf joint with a router.

However, a taper over seven feel from 3/8" to 1" requires a very shallow angle and I realized I could never make two of these accurately enough.

Instead, what I did was cut an 8 foot long 2 by 4  board in half lengthwise to form two router rails. These were hinged on one end and mounted to a wider flat board.

The opposite end could then be raised as desired to get the appropriate angle needed.

Then when the wood to taper is placed between these two rails, the router can cut the taper. Fairly simple concept, however, execution was a bit more difficult.

To start, with the hinged end mounted directly to the flat board, the angle came to a thin end, but I needed my rail no thinner than 3/8". That mean I had to move the rail back sufficiently in order to get to a wider part of the angle.

Because the jig is only 8 foot long and I needed to cut a 7 foot taper, this movement placed a significant portion of the tapering area outside the jig rails. The solution was to mount the hinges on 3/8" spacers.

A few additional problems cropped up. The jig was so long that it drooped when mounted to my table saw / portable work bench. I had to put supports (using cinder blocks and wood) under each end. The thickness of the router guide rails was decided upon to try and prevent bowing in the center. However, this thickness was too thick forcing me to slide the router bit nearly the entire way out of the router's chuck. This meant I had to go real slow while cutting the taper to prevent chattering and periodically check to insure that the router bit was still firmly held by the chuck.

Cutting the jig rails to a thinner thickness, would have left them with more tendency to bow under weight. Nonetheless, if anyone copies this approach, I recommend using thinner jig rails. But support them at various points along the length.

During routing, I had difficulty seeing the wood remaining that needed to be cut. I tried darkening the wood with a sharpie prior to cutting but it was still difficult to see what remained to cut and that experiment was considered not worth the effort.

Once the various challenges were overcome, the jig looks like this. This photo doesn't yet have the support under the near end of the jig. I also added more clamps to better hold the parts in place.

It took about an hour after setup to taper the part. One problem I had, was caused by attempting to taper from the thin end. When I got to the point where the second lamination was nearly done (near he end of its taper), the wood started chipping out. I tried going from the thick end of the taper and this worked better.

Today, I performed remaining fitting tasks, sanded, cleaned the parts, and installed the starboard rail (first lamination only). This was fairly straightforward, the parts was epoxied and screwed into place. I made sure to make he new screw holes in locations that did not conflict with the screws in the bottom and side skins (the blue tap has these locations marked). I also marked the locations of the screws holding this first lamination as i will need to avoid them when I install the second lamination (unless I can get them out after the epoxy cures).

In this last photo, you can make out the side taper which is the look I was after.

Because the spray rails, are rectangular in cross section, and because the plywood skins are rounded at the transition from bottom to side skin, there is a significant gap between the rail and the skin after mounting. This was expected. This gap will be filled in with thickened epoxy later.

What may also not be apparent is the angle at which the rail is in relation to the hull bottom skin. It turns down somewhat from the skin. This next photo illustrates this. When the second lamination is added to this rail, this will be more pronounced. This downturn is intended to deflect the water away from the hull when the boat is in motion.

So that's it for now. I'd like to glue the second lamination into position, but at the moment, there is no one here to aid in the installation. For the most part I can do this myself, but it helps to have someone to support the other end after the epoxy is applied to avoid getting it all over the boat. Perhaps this evening. Take care.

Sunday, January 24, 2016

Spray Rails - Part 1

A combination of colder weather and a difficult time in visualizing the finished product have kept me from making more progress. But I am gradually getting the spray rails figured out, and with each step, comes better understanding of what I need to do.

Let me explain this a bit. Spray rails on this boat can be rectangular in cross section from front to back. They can be full width and full thickness as well. However, I feel that would not look as nice as spending some time to add a bit of shaping to the parts.

Specifically, I want the forward end to taper in thickness and in width gradually until the full 1 inch thickness and 1 1/2 inch width. At the same time, I need to insure that the bottom outer edge remains sharp so that it performs as desired. There is the curve of the hull to consider as the part wraps around the hull. I want to insure that the parts line up when viewed from the front while maintaining a pleasant and gradual curve to the aft a section (which is straight). And finally, the upper surface (the side away from the bottom skin), I want to taper into the skin so it doesn't look so clunky.

Here is a drawing illustrating  some of this.

All of this means that there is a lot to think about and for me at least, difficult to visualize until I get it temporarily mounted on the boat. In order to do that, I need the pieces to be long enough. The longest lumber I could get was 16 feet, so some scarfing was required in order to get the full 22 feet needed.

What I have been doing is working on getting the parts temporarily mounted so I can better visualize the end product and get a better idea of where the tapers start and end, as well as how gradual the tapers need to be. Of course the tapered front will need to transition into the more trapezoidal middle and aft sections. Trying to do all of this by myself presents a few challenges since gravity has other ideas about parts off of the ground!

Additionally, since the rails are 1 inch thick, I elected to do them in two laminations of 1/2 inch thick in order to wrap around the hull curve easier. Of course this complicates the tapering since I plan to do this off the boat before the parts are mounted.

The end result, I hope, is a nicely tapered spray rail at the front, gradually blending into the more rectangular sections at the back. At the same time, the rail will still be functional and serve it's intended purpose of deflecting the water while underway. In reality, only the first 2/3rds of the rail performs this function and the aft 1/3 section is purely optional. But I want it there to give a nicer finished look to the boat.

My progress was hampered by one other factor as well. I misjudged how much lumber I would need and am short. It took me a bit to figure out how much extra is needed. This is mainly a problem because I needed at least two full length pieces in order to verify that they both line up at the front. The only way I could get two full lengths was to cut into one of the second lamination pieces to get the additional lumber needed. Otherwise, it will be at least a week before I can get to the lumber yard to get more wood. Didn't want to wait that long.

Anyway, I have all of that worked out now. I've figured out how much of a thickness taper I want and how the top outer edge of that taper will blend into the aft section. Now I just need some more warm weather and time.

So that's it for now. I wish I had more to write about but I am trying to get there. Better to go slow and get it the way I want it than to rush and not be satisfied with the end results. Take care.

Saturday, January 9, 2016

Skeg Work

I had hoped to complete work on the skeg before posting but the weather is not cooperating, so I've decided to post a status report on work completed so far.

The skeg is the fin that extends down from the center of the boat to provide some semblance of control when in turns. Essentially, it is supposed to reduce the amount of hull sliding in a turn.

For the Vera Cruise, the skeg is an 11 foot long piece of oak tapered from a height of 3 inches at the aft end to approximately 3/4 inch at the front. I covered making this part some time back, but it's been setting in wait until the fiberglassing of the hull was completed.

Installation is relatively straightforward involving 8 bronze 1/4 inch carriage bolts. The holes for mounting had been previously drilled into the skeg and the hull prior to fiberglassing. They had to be cleaned out after the glassing was completed. Afterwards, the area was taped off to limit the overflow of epoxy from installation. I also had to do a minor filling of a bit of damage to the front of the skeg.

The skeg was going to get epoxied to the hull in addition to the use of the carriage bolts However, I wanted to insure that there was a seal coat on the mating surface as well, so this was accomplished first.

I used thickened epoxy to do the gluing. With a bit of help from my wife, who held one end of the skeg up in the air, i was able to get it lined up and a couple of bolts slid into place. Then it was a simple matter of adding the remaining bolts, adding washers and nuts to the ends extending into the inside of the hull, and tightening them down.

The plans call for filling the carriage bolt holes with epoxy but I had previously drilled them out using a 3/4" counter bore which allowed me to fill them with 3/4" oak dowel rod. Since the skeg is getting painted, I was not concerned with matching end grain on the plugs with the grain of the skeg. These were epoxied into position.

After curing, I sanded them smooth on the skeg.

I also wanted to add a layer of fiberglass to the skeg as added protection against bumps and water intrusion. Getting the glass to lay over this was a bit of a challenge, and in fact after glassing I ended up having to cut a couple of small pieces (approximately 3/4 inch in length) away because they pulled up away from the oak during curing. I lay the fiberglass over the skeg and taped it to the hull.

My intention was not to overlap onto the skin, so I did not add fillets at the skin / skeg seam. But to make it easier to install the glass, I did overlap the skin initially.

Epoxy was applied and allowed to set up for awhile. Then I went back with a straight razor blade and trimmed the fiberglass at the seam.

For the seam, I am going to add thickened epoxy in a fine bead and smooth it out. Then the entire skeg and immediate area will get one final coating of epoxy.

However, because of the two areas where the glass lifted, I will first have to do some repairs. This is where the weather got in the way. The temperatures have dropped too much to do any more epoxy work. The skeg has been smooth sanded and the two repair areas have been taper sanded in preparation for small pieces of glass. The epoxy that has spilled onto the skin has also been cleaned up.

Once I can get back on the project, I will complete this work. I still need to apply a couple of fill coats of epoxy before doing the seam work. I am not sure at this point how soon I can get back on this.

In addition to the work on the skeg, I started working on the spray rails. I don't have much to show on that task yet so I will leave it for another day.

Winter has been a slow time for construction since I started three years ago. I have a propane heater for the garage now, but it is not adequate for doing epoxy work . It is adequate for other types of work , but there has not been much of that lately.

Anyway, that's it for now. Take care.