DIY Plywood Bowtube

Most catamaran bowtubes are alum. or carbon mast sections. Some builders are getting shocking quotes to get these built, so they are considering ply/epoxy bow tubes.
I do urge using the best plywood and do not skimp on construction as this is a mission critical part of your cat.
One thing, ideally the tube end bolt would be not 90 degrees but parallel to the hull. I am assuming the hulls are rigid enough that the delta is not significant enough to upset that pin.

Corners are biaxial roving.  The red is biaxial bushing.  Blue is triaxial.  Yellow is the stainless.  There will be cross laminate to hold the triaxial onto to the box.




Venturi Vacuum Pumps

I got my venturi pump at Fiberlay. I understand that even though they sell them there, the pumps are not on their website nor in their catalog. They are not wildly net savvy there.
So the venturi pumps are called Vacuum Generators. Part number 1807003 at Fiberlay, listing for $110.50. They pull 27″ of mercury at 90 psi on your compressor. They only pull 2.2 CFM so the vacuum bag has to be good. No moving parts. I’m a big fan of mine. Call Fiberlay at 1-800-942-0660 or find email at


OLED – Organic LEDs

I read in Automotive Design magazine about new organic LED lights by OSRAM, that are as thin as 1.4mm. They will allow tiny cars to have more trunk space as the tail lights will simply be a film attached to the car.  They can be programmable also for a variety of lighting schemes.  I see a big future for these in multihulls also. I’m sure my multis in the future will have many.


Ziplock Space Bagging

I had kind of a minor breakthrough yesterday vacuum bagging a first part (of 45) for the lander’s top dome. Typically when vacuum bagging, you put the part into the bag and run the vacuum for 6 to 10 hours, depending on temperature.

I have seen the Ziplock Spacebags keeping a quilt vacuumed for what, 6 months? I wondered if it couldn’t be also used to vacuum boat or spaceship parts. Yes, it worked. My concerns that it could not stand my high vacuum pressure, or that the shutoff was tricky, were unfounded. I did create a kind of plastic airlock around the bags shut-off valve so that I could keep my high vacuum longer. I ran the high vacuum pressure 8mm hose through the airlock bag and into the jaws of the shut-off valvve. Next I started the compressor and got my 25 inches of mercury vacuum from my Venturi and compressor. Finally, and in one flash move, I pulled the hose out of the valve jaws and closed them. The next morning it had held the vacuum all night.

My parts are small for this job (2’ on a side) and the bags are also small (3’ x 4’) but with proof of concept, I can start to replicate on bigger parts in the future. Also this means that I can vacuum bag several parts at once as they only need to suck for a couple of minutes.

Bag sucking, showing “airlock” I added.
The bag the next morning.
Bag closed but not yet sucking

Container Cat

Just finished schematics on a fun one. An 85′ sailing container cat for Carribean. Side loading this version. Carries 4 40′ containers. Also carries a few passengers. Between islands, skipping the major ports.  1500 hp per side.  An aeroesque unstayed mast system.


New Design Books

Have I really been doing the Design Books for 30 years now? First one was suggested by notorious seadog Chris Ancliffe.

I have just gotten several orders for the Design Books: and I have run out. Of the 2012/2013 books. I will be doing a new printing of an updated 2014 book, but I have to get to anxious design customer’s work done first.  I expect to start sending about New Year.  I expect Amazon is in the future, but don’t have time to set that up yet.


Holiday Discount

I see it’s time again for the annual holiday plans set discount. Matthew has had a lot on his plate, as they say, but I understand it will hit on or about December 15th. The discount will be built right into the plans price at the shopping cart.
There will also be changes to the study plans.  As noted before, it seems that all I can accomplish anymore is email and special situations that happen to study plans orders. Study plans will now be $100 plus shipping. An option for PDF study plans will be added, for $50 and no shipping cost. They also include appropriate spreadsheets and word files.