All posts by Kurt

Lake Chelan Ferry Molds

Amazing rapid construction by Albert, the Thain Boatyard shop lead. Not everyone might understand that this female mold is developed plywood, with minimal fairing. I had been doing this with CM before, but Albert simplified it even better.
He CNC cut out the stations, then tortured a single layer of 4mm ply into it.
That is huge time savings. It becomes a big 3 D batten.
The other shape is the strip planked deck mold. It had to be done the old ways.  It looks like to could also be a party barge mold.

inside the ferry mold
outside the mold
the strip planked deck mold

Lake Chelan Ferry

50′. Foam glass hulls. Ply/core/ply cabin showing bright wood inside. Carbon added to plywood to save weight where reasonable.
A pair of 140 hp outboards to give 20 plus knots.
Lake Chelan is right up there with Lake Tahoe as a deep, scenic, crystal clear lake.


I got back from out of country to a truckload of rush projects. This blog fell behind.
Besides getting autocad files of hull lines to Owen, a new 50′ ferry for Lake Chelan in Washington here, a 79′ charter cat in Mexico, finishing up the new 79′ Sierra Cloud for Lake Tahoe, a new wingmast design, more on the 45 cat, and several little ones.

I did see that the heavily marketed Rapido 60 trimaran was only in the middle of the E-glass fleet in the ARC race when it lost it’s mast. I understand that no other masts were lost.
I also saw that Russell Brown took great exception on SA to my doing commentary on designs.
There should be some quiet here during the holidays where I can catch up.
Also, I keep the hot shot workstation off of the net. Just to be sure. My web machine is an ancient Pent4 using XP. Anymore it slams up to 100% CPU use as soon as I turn it on, and stays there. Everything is a big hourglass.
Nothing I’ve tried is able to cure that. It seems the antivirus software takes most of the bandwidth. So I bought a new computer. The handoff of programs, database, email and varous peripherals may or may not be seamless.  I will try.

Email Jamup, Again

Almost 1000 spam came in over the weekend. The online computer is choking on it, as well, the antivirus software keeps uploading new anti definitions. So, I may have to get back to some of you next week.
When Outlook crashes, it starts loading the whole lot from the beginning again.
I see a new web computer in my future. This one is pretty old. I do keep the workstation off line.

Fish Expo Time Again

And again, they have gone upscale and now call it Pacific Marine Expo. Fish expo it will always be to me.
Nov. 16 to 18th. Century Link Field Event Center. Seattle.
It is a PNW event, but mariners can always be heard speaking a dozen languages there.
It is the serious boat show.  I can’t find the link.  Google it.

Rapido 60

When the Rapido 60 trimaran first appeared, I figured it was some kind of a joke. The styling recalled an F27 from 20 years ago. I teased that they owed Ian royalties. It’s beam overall was just over 38’, which some of mine, and most modern 40’ + trimarans, equal.  My GS 60 beam overall, from 25 years ago, in E-glass, was 44.5’. Everybody knows that when you push a multi, wide is what keeps you right side up. So making it not wide had to be something to push onto the unsuspecting, right?

Almost all the pictures I saw of them had the crazy camouflage paint so it was never clear what was going on. I figured that they were not serious and didn’t think much more about them.
It was just pointed out to me that the R60s don’t have continuous mainstrength beams. Blew me away. Followers of this over the years have seen the importance of continuous fibers, fiber orientation, co-curing of mission-critical parts, not forcing composites into sharp turns…..
And here is one design that seems to ignore all that. What gives?
And that explains the narrow overall beam. That’s the only way to keep the loads down, besides throwing carbon at the problem.

Again, I have always declared that with enough carbon and enough money, one can have almost anything designed. This seems to be a prime example.
If we assume 24,000 lbs sailing weight, and a 12’ cantilever of the beam, then hit it with a shock load on one of the beams. The moment at the root will be something like a quarter million foot pounds. If the bury is 3’, then the load to resist will be some 80,000 lbs.
No wonder it is so heavy. Yes, heavy. 20,000 lbs. lightship. It is all carbon, right? That carbon has some 5 to 7 times the modulus of E-glass. Compare to my GS60 at 13,000 lbs., as designed, in mostly E-glass.
Main point. You can’t beat a continuous D section for the most beam strength and stiffness, the least weight, and least cost to build.
And again, all boats inhabit a place on a continuum between a habitat and a vehicle.
The R60 seems a bit confused.  All the carbon tells me vehicle, but chopping up the lightest, strongest possible connecting beams to get more cabin space is right back to a 1960s Horstman; habitat.
None the less, I’m sure they will sell a lot of them. The owners can “Hey baby, I got a carbon boat.”
I prefer direct, simple solutions to magical ones.

VHB Tape Fail

Part of what I am doing on the lunar lander dwelling project; building a tiny house using boat construction, is to test the limits of many techniques and products. I took the VHB tape past its limit.
I tried to use it to attach an acrylic shower door without any fasteners; a worthy goal.
While the VHB tape is amazingly strong, it has limits. Its weakness as I understand it, is long duration loading, while depending on peel strength. The shower door provided that.  It’s tepid resisting the energy of initiation, followed by energy of propagation, made it fail.

In the picture, the VHB tape attaches both the hinge and the angle brackets.  Both failed after a while.
On a window, peel strength would not even enter into it. I’m always curious about where the real world limits are.

40 Foot Performance Shorthanded Trimaran for Owen

Use program:
Shorthanded sailing for both racing and cruising.
Demountable and able to fit into a tallboy container.
This design is the latest update to a design that I did several years ago for Phil Steggall.

It also has several features that I developed while sailing my own F40 Geko. First of these is the addition of an actual cabin from main hull flare. Any time a few people come aboard for a sail, their gear has to go somewhere, The 7 foot wide cabin also allows a canopy to hide under in bad weather. On the much narrower Geko, that space was taken up by winches.
The outboard is mounted beside the cockpit instead of back on the transom. When shorthanding having the motor right there without leaving the cockpit is important. On the Geko an 8 hp outboard would push it to 7 knots in chop and once did 11 knots on flat water.
It has a single board in the main hull. Vertical and aft of the mast a bit. In Marchaj we find that a vertical board has the most even stall characteristics and also less deflection for the span. Fully down, the board is a couple of feet below the cabin top. Downwind the boom can be lifted a couple of feet to reduce board draft. I don’t understand the trimarans that suffer the inefficiency of swept boards.
Board down, the draft is something like 10 feet.
As usual it has 200% buoyancy amas.
Presently the design has ama rudders.

Foils were not chosen as they work best with larger crews.

Construction is strip foam and unidirectional e-glass for the main hull. The amas could be the same or even a combination of developed plywood and carbon fiber.
Beams are core with carbon fiber.
Geometry is virtually square with the width almost a much as the length overall.  Doesn’t that make it wider than a Rapido 60?

IBEX 2017

I did see that it did go on despite the exciting weather. Did anyone go and anything to report?

I was also pissy as I thought a house built almost entirely like a boat, and permitted, would be a great topic.   Epoxy, foam, vacuum bagging, BS 1088 plywood, biaxial roving,  glass gloth over everything, 12v electrics, stainless fittings, 2 part poly paint, Beckson ports.  Technology transfer.  IBEX powers were completely uninterested.