Monday, August 30, 2010

Minding the Gap

We had a great time at the PNW Westsail Rendezvous last weekend. Despite being unable to stay very long. But still, it is always inspiring to meet/talk to fellow owners and sniff around their boats. Even though they are same "models" everyone's boat is different. Owners continually make changes. I am sure we will be the same.

Anyway, speaking of inspiring talks... we chatted with Dave King about his Pacific Cup winning Westsail 32 "Saraband". He said the boat has gained nearly a knot by doing some simple underbody fairing mods to improve laminar flow and reduce drag. As he described it, it sounded quite easy to do, as the mods are not structural. Just simple glass over foam against the existing hull. While not exactly the same thing, this got me thinking about the gap between the skeg and rudder on our W42.

Since we installed the rudder, there is about a 2 inch gap between the skeg and leading edge of the rudder. Enough of a gap that I think would increase drag. If you look at most sailboats in the yard, with skeg hung rudders, the trailing edge of the skeg is often closely molded to receive the rudder. This improves flow and reduces drag. I had been wondering how to fill this gap, or if I should even bother. But one thing Dave kept saying about his mod was "Hey, the boat is already out of the water, and it is an easy project." So, that pushed me over to try something.

After a couple hours on the 3D software, and CNC machine, I had cut a couple shims machined from Coosa fitted and ready to be glued/glassed. I am not sure this will yield a knot gain in speed, but you never know lol.

Modeling the shape of the shim.

Test cut using cheap insulation foam.

Final piece cut from Coosa

Final fit of the shim

Thursday, August 26, 2010

Secret Weapon Revealed Part III: Reality and Building the Boat

This is a blog about building a boat. So, this will be the last I blab on about the CNC machine (well for a while at least, lol)...

To be honest, I felt a little guilty about waiting so long to talk about this machine. The reason  I waited was that I was not sure how significant an application the machine would be to the boat project. Now, I was under no illusions that such a machine would "magically" build the boat. But I kept thinking of project applications before and after it was built. Since it has been running, it has been involved just about every boat project since to some degree. Even with things as basic as template jigs, the machine makes a difference of cutting it in five minutes versus spending an hour doing it by hand. When you are just one guy (and gal) building a 42 foot boat, any time saving measure one can take is very valuable.

One thing this machine has changed is how I look at construction problems. Which should not be surprising I guess.  The more tools you learn to use and add to your toolkit,  the more difference is made in approach to design and construction (you craftsmen out there are probably saying "duh!").

One thing the machine has helped with is "time management" of the project. When you are holding down a day job, you need to make the most of your time in the morning, evening and weekends. And, manage all that with the rest of life's responsibilities. The machine allows my typical work week to go something like...

  1. Stare at the CAD program over a cup of coffee in the morning, have things drawn/designed by Tuesday
  2. Process the cutting files by Wednesday
  3. Machine cut the parts cut by Friday
  4. Have everything ready to build/assemble/install on the boat by the weekend.
 A schedule that works out nicely (especially when, on Monday/Tuesday, you are dead tired from working on the boat the previous weekend).

And finally, there one thing I find amusing about all this. I have yet to use this machine for one of my primary reasons for building it in the first place: fiberglass mold making. Why? I have been too busy discovering other applications!

Tuesday, August 24, 2010

Engine Room Hatch is IN!

In the spirit of trying to cut as many holes in the deck before the rainy season starts... the engine room hatch has now been installed.

Without such a hatch, should you ever need to quickly get into the engine room from the cockpit, you would need to scramble down the companionway, go through the galley, through the tunnel, into the aft head, to the door to the engine room. With this addition, you can open the hatch and drop right in. If you fit that is. I better not gain any more weight or else this may be useless.

I got the idea from Dave on the Westsail 42, Elysium, but took a slight different approach to his otherwise perfect installation.

The flange that supports the hatch and provides the pathways for the water drainage was built from Coosa (instead of molded from fiberglass, as was Dave's method). The CNC machine was used heavily to provide the template for the cutout and for cutting the pieces of the flange. Edges were rounded over on the "manual" router table, and the whole thing assembled in place and glued in with thickened epoxy and thru-bolts.

Final sanding, trimming and paint, as well as choice of latch mechanism, will be done when the deck is refinished (not this year).

For completeness, here is the slide show...

Secret Weapon Revealed Part II: The Machine

So here are the basic list of features. See the slideshow at the bottom of this post for closeups of the machine.

  • maximum 4 feet by 4 feet cutting area (larger can be cut with a bit of cutting file trickery)
  • high speed lead screws give linear motion up to 300 inches per minute
  • hardened steel bearings ride on rails of steel angle stock
  • spindle is a Porter Cable 7518 3.25 hp variable speed router
  • stepper motors that drive the lead screws are of the high torque variety
  • Gecko G540 motor controller running at 48VDC.
  • a Dell Inspiron laptop (inherited) drives the table using Mach3 software
  • the table has mechanical (rail clamp system from Rockler) as well as vacuum hold down (made from PVC pipe, ultra light mdf and a shop vac)
  • a special dust shoe (made by the machine itself), clamped to the router, around the cutting bit   connected to a 4 inch dust collection hose sucks up the chips and dust during cutting (note, the dust collection system was already in place for a couple years)
  • The router and vacuum table are switched by software.

Since the machine has been up and running, it has played some role in pretty much every boat construction project since. Whether it is cutting parts, templates jigs, etc. Some samples are

  • Shop cabinets. All pieces, shelf holes, hinge holes, doors were cut with the machine. This was the first project where I got to know the ins and outs. The cabinets did not come out perfect, but I learned a lot about calibrating the machine and using different style bits.
  • Dive tank and propane tank locker. The upper and lower pieces of the tank assemblies, cut from Coosa board, where cut using the machine. This made the building of the assemblies quite easy.
  • Templates and jigs. The machine was used to cut plywood jigs to help spot and cut the openings in the deck of the boat for the dive tanks, propane tanks and cockpit coaming compartments.
  • Anchor bow roller assemblies were mocked up with pieces cut from plywood. All cut from the original CAD designs of course.
  • Deck hardware backing plates, cut from 1/4" aluminum plate. This machine can cut it, albeit VERY SLOWLY.
  • General cutting operations. Like when you need to cut that odd size hole where you have no appropriate hole saw
This machine is certainly not "production quality", it can't be run 24/7, lead screws need frequent lubrication and bearings need to be tightened often. But for the price and for this boat project, it is a perfect fit.

Next, Secret Weapon Revealed Part III: Reality and Building the Boat

Saturday, August 21, 2010

Saturday Matinee

Here is a demonstration of the CNC machine's basic capabilities. This time compressed video is of the machine cutting a part for the under-deck flange for the engine room hatch, a project that is currently in progress.

This video shows some of the basic operations such as drilling holes, cutting pockets and dados and the final cutout. Straight and curved edges.

There are more videos on my YouTube channel

Tuesday, August 17, 2010

Secret Weapon Revealed Part I: Cunning and Deception

A new tool has been added to the shop, well, added last fall actually. This is a CNC router table. 'CNC' stands for "computed numeric control". It is basically a computer controlled router table that can cut pieces designed in CAD. It can cut your basic two dimensional shapes and do some three dimensional stuff with the necessary software.

I built this last fall using unistrut, MDF, UHMW plastic, steel and aluminum extrusions, and a number other parts all easily sourced from your local Home Depot/Lowes and the Internet.


A few years ago, within the first year we acquired the Westsail as a bare hull, the admiral and I attended the IBEX marine builders trade show in Miami. There were numerous companies showing off their production quality CNC cutting machines. I was drooling. My wife kept hitting me in the arm and saying "we don't need one of those!!" With average prices starting around $45,000 she was right. Nevermind that we would not have the floorspace for one of these things. But still, I was drooling. Over time, I kept looking at these machines. I came across a "hobby grade" machine,, but the prices were around $20,000. Still too rich for my blood.

Cunning and Deception

Then sometime last year, whilst browsing, I learned of a DIY CNC table design called "Joe's 4x4 Hybrid CNC". The plans could be purchased for $100, and, the more critical custom parts could be purchased for $400. With that you got access to the Joe's CNC forum were other machine builders describe their tips, tricks and modifications. The trick here was how to sell this to the wife (here comes the cunning and deception bit). I started with purchasing the plans to research what the machine could actually do and how it could be applied to the known remaining boat construction projects, with which I would occasionally mention "You know, a CNC machine would really help with 'xxx'" But I don't think she bought those arguments. At the same time I was slowly selling stuff on eBay that was piling up in the garage that I knew we would not be using, to help pay for machine build costs.

As I was quietly accumulating the necessary hardware to at least start the base table, one week while my wife was out of town, I started assembling the base table out of unistrut. Of course I got an earful when she came back when, despite my assurances that I was trying to control costs as best as I could, she pretty much resigned herself and said "well, you are going to do what you want anyway". I felt really guilty, but I knew this machine, when complete, would be really handy for stuff. I just could not prove it.

So, for about two months I acquired parts,selling eBay stuff and paying cash all long the way (as best as I could), and spent every other weekend assembling, squaring, aligning, gluing, sanding and painting (with some unplanned dis-assembling and re-assembling), all under the suspicious eye of my wife. Just before Christmas 2009, I had a machine ready to be fired up. Total cost: about $3000.

It's Alive!

I connected up the electronics, fired up the software and did some initial calibrations. Movement! Shortly thereafter I had the machine doing some test cuts on cheap plywood. Soon, I had the machine cutting the final parts, that would ultimately be used the machine. After witnessing this, my wife later came up to me and said something like "Wow, thats pretty cool, can it cut a 'XYZ' part for one of MY projects??"  I took that as evidence as she was finally sold on the idea.

Yes, we are still married.

Next in Part II: Tour of the machine.

Tuesday, August 03, 2010

Working with C4

No, not a new construction technique involving explosives...

C4 standing for "Cockpit Coaming Crap Compartments"

Whilst sailing in our little 28 footer the cockpit often accumulates various items such as winch handles, handheld GPS, handheld vhf, sunscreen, autopilot remote control, sailing gloves, and numerous half consumed bottles of water (the crap). The small boat has cutouts in both sides of the cockpit coaming (which is basically the "backrest" of where you sit) handy for storing these items. Close enough to throw stuff into and retrieve from without taking your hands off of the helm. The original Westsail 42 did not have any handy storage for this stuff in the cockpit area. So we added some. Two holes cut into the port side coaming and walled in from the underside. We elected not to do the starboard as it is above the "tunnel" to the aft cabin and may look odd from the inside. Besides the one port side compartment should be big enough.

Walled in with coosa board, glass and epoxy with the inside corners filleted with thickened epoxy, it passes the leak test (I tossed a gallon of water in there with no leaks into the engine room). The compartment is positioned to allow for winches (including electric winches), mounted on "top" of the coaming, fore and aft. The forward wall has a hole where a ventilator fan will be mounted to help keep the engine room cool.

Still To Do

  • strategically spot a drain hole or two (to the outside of the hull) to keep the compartment dry
  • sand and paint the inside. White? grey? something in between?
  • fabricate and fit removable "doors" to the compartment. Perhaps locking. I need to see what sorta hinge hardware is available