For the very latest activity, click here: From a Bare Hull

Saturday, March 31, 2007

In Search Of A Rudder (Part 1)

The Original Westsail Rudder Design Well, I don't know how long it has been since I blogged about the rudder. I think the last time I did I was looking into what it would take to build one from the original drawings. I had taken a copy of the construction drawing for the original steel rudder frame over to my stainless fab guy. It calls for half inch steel plate.
He looked it over and initially said "yeah, it could be made".
Then he said, "Wait, how big is this thing?" (the drawing was not to scale and the dimensions were hard to read).
"It's about 5 feet tall" I said.
He comes back with "Do you know how much this will weigh? Just the steel? That is about 500 pounds! I can't build that. I don't have the equipment to move around something that heavy!"
To which I responded, "Yeah, you are right. Never mind what it takes to build it, but do *I* want to move something this heavy around when it is done?"
That pretty much ended the pursuit of a rudder along the original design. The two images you see here are the original Westsail designs. Pursuing A "Newer" Rudder Design So, I started thinking it over and did some research into rudder design, foil shapes and construction techniques. Most of what you find is targeted towards racing boats with spade rudders. I didn't find much on full keel skeg hung rudders. This was all very interesting, but I realized, a rudder is not something on which to take risks, and I don't have the time to do the engineering work. Besides, I thought, rudder design and construction MUST have progressed a way in the last 30 years since the original design. So, we decided it would be best contact someone who has experience in this area, instead of trying to hack it ourselves. So we rang up Bob Perry's office and set up a meeting. We brought a copy of the original sail plan and drawings of the original rudder design and build instructions. The first hour was almost comical as Bob was looking over the drawings, he started muttering things like
"What's THIS for?", "Why did they do THAT?", and "Why didn't they do THIS?"
So as we started talking rudders I asked,
"Can you improve on the original rudder design?"
"On this boat? Not by much!" he responded.
Judging by his tone I believe he was thinking "These two crazy people are expecting a redesign of this rudder is going to make this boat faster!"
Once I realized this I said, "Look, we are not expecting a new rudder will turn this into a racing boat!"
"But why do it?", he said.
"Because we don't have a rudder, AT ALL!"
At this point his tone changed and everything clicked. Obviously, we did not make clear that we have no rudder.
With that confusion cleared up I said, "This original design will weigh 500 pounds! If you think this is a good design, then say so. But I would rather not lug around a 500 pound rudder if we don't have to!"
He paused,
"...nah, we can do better."
So, that was pretty much that. We stayed and talked with him and his engineers about other things nautical. This was a few months ago, since then, his engineer Tristan has been working on the drawings. We picked up the final drawings last week. Tristan did great work. I will post more info about that in another entry.

Wednesday, March 28, 2007

Main Salon Floors Framed

The last couple weeks saw the cutting and framing of the floor for the main salon. This will support the main floor as well as house the main fuel and water tanks. Material is 1 1/2" Coosa BW 26 (the stiffest stuff). Measurements for the curvatures was done similarly to the bulkheads. The laser measurer was taken every few inches from a common plane spanning the fore and aft bulkheads. Measurements then plotted in CAD, full size templates were printed, then the Coosa was cut from these templates. All worked pretty well with only a couple minor trims needed. The Coosa is held together with 4 inch stainless tapping screws (square drive, of course!) and structural adhesive was used at the joints. This is of course just to hold it together. Next, the final installation will be tacking it down with structural adhesive then tabbed to the hull with glass and resin. A note that the overall width length and height is larger than that on the original Westsail 42 drawings. Tank capacity underneath is approximated at 500 gallons total. But that is a very rough estimate, it will likely be less. The center tanks will not run completely to the bilge, there will be space to run some plumbing underneath.
The floor plan PDF link on this blog has been updated (link on the right).

Monday, March 12, 2007

Bilges are Done!

This weekend I removed the main salon temporary floors, to get down in the bilge to finish the glasswork. Recall that, with the keel repair a year ago, the plywood/fiberglass atop the bilge had to be removed. To reseal it, it was covered by a thick mix of resin and milled fiberglass. This left sharp edges and things a bit unfair.
So, to finish things up, I took a grinder to the top of bilge in order smooth off the sharp edges and try to get things somewhat fair. Then, after thorough acentone clean, filled and smoothed over any divets with filler, and covered it with two layers of glass, each extending up the sides 3 and 6 inches.
Laminating large pieces of glass like this is a big PITA. Not to mention, messy.
Materials are on order for the final main salon floor installation. Hopefully this weekend.

Saturday, March 10, 2007

Slight Change in Plans

Like this never happens... After taking measurements for bulkhead templates and plotting them in CAD, I calculated size of materials needed for the fore and aft bulkheads. Total is about 20,000 sq inches. Now, my supplier provides the materials in 4'x8' sheets. However, for strength purposes, it is best to minimize the number of joints by constructing the bulkhead with as few pieces as possible. With these measurements, if they are constructed from 5'x10' sheets, I can minimize the number of joints. Most bulkheads can be made from two pieces using 5'x10's. But this size of sheet stock can only be special ordered. What's more, the size of the pieces are too big to fit through the companionway or through the cockpit floor. So, the current state of things has the main salon floor incomplete, it is still temporary. We have decided to postpone fore/aft bulkhead installation and, instead, finish the main salon floor. This will allow the following to be finished:
  • final measurements for all bulkheads. This will give total sheet stock requirements so we can place one BIG special order.
  • final smoothing and glassing of the center bilge
  • tank spaces so tank fabrication/installation can begin
  • take final hull measurements for CAD to more precisely layout the main salon.

When it comes time for bulkheads (maybe later this summer), we will hire a crane to come in and hinge up the front of the deck off of the hull so the pre-cut bulkheads can be slipped into the boat. Whereupon they can be trimmed and permanently installed.

Speaking of tanks, I ran preliminary volume calculations and came up with 380 US gallons (fuel and water). The original Westsail 42 sales literature (1978) spec'd total tankgage at 456 (US?) gallons total. I was expecting my calculations to be more space efficient and tankgage would therefore be more than original. I cant see where to get 450 gallons under the main salon floor so I kind of question the sales literature. Anyway, we'll see where the numbers end up once we get under there.

Sunday, March 04, 2007

Update: Driveline and Forward V-Berth

Some pictures on the current state of a few things. Particularly the fitting of the shaft and the start of glassing in the forward V-berth. There are a number of external boat projects in progress. Anyway, some pictures...