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

Monday, April 28, 2008

More Foam

Got some more foam cut and glued this weekend. Actually, all but one piece of foam has been shaped. But I ran out of glue. More coming today. Also, the bottom-most stainless "webbing" piece, got a "sacrificial skid plate" attached to the under side. Made of out of 3/4" Coosa and 1/4" G-10 plate (bottom most) the idea being, in case of some sort chafe from grounding, the Coosa, G-10 and the glass laminate that surrounds it, will take the hit first before the stainless frame.

Sunday, April 27, 2008

Annual Pressure Wash Weekend

Yes, fairweather comes to the PNW. At least for a couple days. Rented a 3600 PSI pressure washer and took it to the Westsail, and other things around the yard. This washer was more powerful than the one we used last year. Unfortunately, it was not powerful enough to remove the gelcoat from the deck, which I was kind of hoping (that is a joke by the way, I am still NOT looking forward to grinding off the waffle pattern nonskid from the deck.) Also, the tape I had been using to seal the hull/deck joint to keep the water out had been failing. The UV ultimately got to it. I was surprise it lasted as long as it did. Unfortunately it left a lot of sticky adhesive residue which the pressure washer could not remove. Not a big deal at this time. But I do need to devise an alternate method for keeping the rain out before it comes.
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Sunday, April 20, 2008

Proof we arent the only crazy ones doing this...

A fellow who is completing a Westail 32 Kit boat. A bit more in the advanced stages when he bought it, but a build out nonetheless. Give it a view. http://westsail32.blogspot.com/

Wednesday, April 09, 2008

Some Assembly Required

Rudder Frame is DONE!
Got the final rudder welding done over the weekend. Many thanks for Bob and Jan over at Fidalgo Machine, who, not only did the final welding, but also machined many of the bits. Special thanks to Bob for putting up with my questions about all the machining he does. I would love to have a shop like that to play in. If I only had the time.




Anyway, here are the shots of the final welding and the trailing edge G-10 plate. Bob indicated he never built a rudder this heavy and complex (marine rudders and shafting are his specialty). He christened the rudder "La Bamba". A long story that maybe I will post later.


Over The Hump
With the frame now welded, the remaining task for the rudder is lamination. It will be shaped with structural foam, and laminated with about 5 layers of glass. The good news is, we already have those materials, so remaining costs for the rudder is almost zero. Somewhat comforting after paying for the engineering, stainless and machining for the frame up to this point.



Sunday, April 06, 2008

Rudders, Steering, and Wide Angle Geometries

As mentioned in previous posts, we are planning to install transmission steering. One of the other advantages of transmission steering, (over pull-pull cable or hydraulic steering) is the mechanical advantage that can be achieved using wide angle geometry. Basically, the principle lies in the difference in lever arm lengths between the reduction gear box (right in the picture) and the rudder post tiller arm (left). The reduction gear tiller arm can swing through an arc of about 120 (60 degrees port and starboard) degrees. The typical 'useful' full swing of a rudder is about 72 (36 degrees port and starboard) degrees. By aligning the reduction gear, with the tiller, such that are linked in the "full swing" position, something mechanically interesting happens.
When the rudder is at 0 degrees, the mechanical advantage between the reduction gear and the tiller is about 1.5. As the tiller swings, the mechanical advantage progressively increases to nearly 3.0 (almost double) as the rudder approaches "hard over". This can be very useful if you are battling weather helm when underway.
The Jefa website has a more in depth discussion here.
What's more, if one wants the steering "constant", simply aligning the reduction gear, such that it's tiller arm is on center with the rudder post, will reduce the mechanical advantage to constant.
Or, aligning the gear somewhere in between will give you less of an advantage but more than constant at extreme rudder angles.
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Friday, April 04, 2008

Fiberglass Tank Fabrication Part III

In our last episode, things were imploding and our fearless leader was contemplating how he could save the world, er, mold.

Recall, things started imploding as leaks were present between the outer skin of the plug and the inside space.

To try and fix things, I cut out the bottom of the Masonite base to access the hollow interior of the plug. Applied some sealant around the inside corners to help get a good seal. Then I poured in some "dump foam". This is the stuff that comes as a two part liquid. Mix equal amounts, and pour. Within ten or fifteen minutes, the liquid expands many times its volume and cures to form a lightweight closed cell foam. The dump foam gives the mold strength, and helps seal any area that may be the source of leaks. So, once filled, I applied the vacuum. And voila! I have -28kPa pressure (pretty good for this vacuum pump). There was still a very tiny leak somewhere that I could not seem to locate, but I rolled the dice and gave it a go.
Things seemed to go pretty well at first. However, after a while "raceways" were developing along the edges. "Raceways" is the name given to channels that develop where bubbles all of a sudden "zip" toward the vacuum port under pressure. This indicates where resin is freely flowing. The effect of this is as the glass wets out, the resin will travel from the feed tube, to the vacuum tube, along these raceways (a path of least resistance), before other areas of the part are fully wetted out. The only thing to do is to continue drawing more resin through and hope those areas finally wet out.

The next morning, I pulled the bag, flow medium and peel ply. Sure enough, thought not totally dry, parts of the inner layer of glass was starved of resin. For further inspection I started to remove the part from the mold. While the laminate seemed to separate from the surface pretty easy, it was hard to get a handle on things to pull apart. So, being as this is a one-off part, I began to cut the mold into pieces from the inside with a sawzall.

Success? Well, Sort of...

Well, so the infusion did not come out as planned, and the piece as it is, cannot be used as a tank. And I must say, this is one of the more "complex" pieces I have infused so far. But it is not a total loss.

The important part here is getting the odd shape that fits the space where it is intended to go. That is the whole reason for making a custom tank here in the first place! And, since it is just a poo tank, it simply has to be solid and well sealed. Not perfect.

Two Salvage Options

If I really want to pursue and infused tank, I could use this first piece as a FEMALE mold for another attempt at the tank. I would need to do some hand layups of a couple layers at least inside. Then I could smooth it out and try infusion again. And throw the mold away.

Or, I could do the hand layups. Make sure it is sealed well, put a top on it. And have a tank! Not wanting to dwell on the infusion aspect too much, I might opt for the latter and simply finish it with hand layups as a tank.

Lessons from this Project...

The Colbond flow medium I used (blue random stranded material layered outside the peel-ply) should not be used around the edges of the part, as when pressure is applied, it compresses the medium inside the bag and creates a small channel that runs along the edges. This is what created the "raceway" which helped the resin reach the vacuum port before other areas of the part were saturated. I should have cut the flow medium only to cover the face of the sides up to about an inch from the edges.

Next time, I will used multiple vacuum ports, with valves, which will enable a degree of control should one part saturate faster than another. Ports could be controlled to help "encourage" the resin to flow to other areas of the part.

Larger vacuum lines. I used 1/4" ID hose this time. Next time I will use 3/8" ID.

Continuous strand mat. I was thinking about using this over the final layer of glass, but decided against it. In addition to adding strength, it would have helped resin flow. I will try that next time.
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Wednesday, April 02, 2008

Westsail Links

Be sure to check out the sidebar section titled "Links". In there you will find a number of boating related links we tend to frequently visit. Also listed are a number of other Westsail owner sites. Of note in particular is Dave's S/V Elysium site, documenting a remodel of his Westsail 42. He has really done quite a bit to his W42 and his work looks top notch. Be sure to check it out. If you know of any other Westsail owner sites not listed, be sure and drop a comment! Enjoy.