Kaimusailing

s/v Kaimu Wharram Catamaran

Vessel Name: Kaimu
Vessel Make/Model: Wharram Custom
Hailing Port: Norwalk, CT
Crew: Andy and the Kaimu Crew
About: Sailors in the Baltimore, Annapolis, DC area.
23 February 2024 | St. Marys, GA
15 February 2024 | St. Marys, GA
11 February 2024 | St. Marys, GA
06 February 2024 | St. Marys, GA
26 January 2024 | St. Marys, GA
14 January 2024 | St. Marys, GA
09 January 2024 | St Marys, GA
23 December 2023 | St Marys, GA
10 December 2023 | St Marys, GA
25 November 2023 | St. Marys, GA
17 November 2023 | St. Marys, GA
17 November 2023 | Somers Cove Marina, Crisfield, MD
03 November 2023 | Somers Cove Marina, Crisfield, MD
26 October 2023 | Somers Cove Marina, Crisfield, MD
17 October 2023 | Somers Cove Marina, Crisfield, MD
11 October 2023 | Somers Cove Marina, Crisfield, MD
04 October 2023 | Alice B. Tawes, McReady Pavilion, Crisfield, Maryland Eastern Shore
03 October 2023 | Alice B. Tawes, McReady Pavilion, Crisfield, Maryland Eastern Shore
03 October 2023 | Alice B. Tawes, McReady Pavilion, Crisfield, Maryland Eastern Shore
20 September 2023 | Somers Cove Marina, Crisfield, MD
Recent Blog Posts
23 February 2024 | St. Marys, GA

D4 Inside Seams

Day two of the dinghy build started out with me finishing wiring the hull bottoms together on the centerline of the bottom panels. This was much easier than the wiring of the chine edges of the bottom panels and the side panels.

15 February 2024 | St. Marys, GA

D4 Dinghy Day One

A Wharram Pahi 26 had been anchored in the river nearby the boatyard and was hauled out with the travel lift. I went around to look at it and talked to the owner couple. I was surprised that it had been built in Martinique in 1988. The boat is more than 30 years old.

11 February 2024 | St. Marys, GA

D4 Redux

The inflatable (deflatable) dinghy I had bought was deteriorating. It had bottom seams separating. It is a West Marine branded dinghy made out of PVC. HH66 is the adhesive to reattach the seams. A friend had a similar problem and bought the same adhesive. I was waiting to hear from him how it worked [...]

06 February 2024 | St. Marys, GA

The Clincher

We decided to go to Amelia Island for the day, probably to the beach. Our plan to cycle around on the Raleigh 20’s seemed like a bad idea, Bleu can’t keep up with a bicycle for very long and when he quits he quits. So we would walk, where?, Fort Clinch State Park. She has a forever pass for Florida [...]

26 January 2024 | St. Marys, GA

Zen and Bike Maintenance

Eloisa rolled into the boatyard after a long drive down from the mountains. It was getting cold and isolated up there. I had a nasty toothache and we went to Southern River Walk. Bleu, her black American cocker was showing a bit of plumpness. I had had a sandwich and some wine already, so I didn’t [...]

14 January 2024 | St. Marys, GA

Sink the Bismarck

I continued reading Richard J Evans - The Coming of the Third Reich. It is chilling to read how a cultured, disciplined country can descend into a horrible Armageddon, not once, but twice, and bring the whole world into wars of might and ignorance. I don't know politics, but this book is a revelation. [...]

#4 Beam Pt I

18 June 2013 | Bodkin Inlet/Chesapeake Bay
Capn Andy/hot, humid, T'storms
The rear crosstube was remounted on the repaired sternposts, bedded in silicone sealant. Now the work could turn to the #4 crossbeam.
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The original plan for the crossbeams of the Narai MKIV show layers of 1” wood encased in plywood and glassed. The original scantling for crossbeams is much smaller than the scantling of Kaimu's existing crossbeams. The original crossbeam scheme didn't work out all that well, as several articles of Sailorman and Sea People magazine show. Beam rot is a common affliction. At some point modifications to the Classic polynesian catamarans introduced wider overall beam, and thus, longer and heavier crossbeams. The additional laminations of 1” wood and wider planks used in the laminations created the larger beams, such as Kaimu has. There was no encasement of plywood. At this time Wharram began to lighten beams, dispensing with the crude balks of wood of the originals, making more artistic beams, rounded and hollowed, and glassed heavily. Later the Tiki series had beams that were I-beams with a fillet on the inside of the I, producing more like an X-beam.
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An old sailor, designer, and boatbuilder named Tom Colvin did most of his work on the Chesapeake. His book, I think called “Cruising Wrinkles”, had lots of information of his style of sailing. One point he made was that fiberglass over wood was not a good idea. He thought the scantlings should match, if you had a large piece of wood, then you'd have to put a thick layer of fiberglass over it. I think he was right. What I've seen is plywood with a fiberglass sheath seems durable, even polyester glass. Larger pieces of wood seem to suffer unless the glass sheath is rather thick. Some resins matrices expand and contract more or less than the wood substrate. A tiny crack anywhere in the sheath allows moisture infiltration which exacerbates the problem, especially when there is freezing/thawing cycles. The sheath gets further compromised and the wood underneath starts being exposed to moisture and oxygen. Any fungus spores around start their work and the wood starts losing strength. All this takes place under the protective glass surface, and eventually, the fungus starts sprouting its fruit bodies or emitting stained liquid. If the wood hadn't been encased in the glass sheath, any deterioration would be evident right away. New wood can be glued in place and the bad wood can be cut out. Anything can be repaired this way. Fiberglass has great tensile strength, much greater than wood, but it is heavy. Usually an equally strong part can be made of larger piece of wood that is as strong as the smaller fiberglass and with less weight. In our case, we already have increased size of the beam, let's make it out of wood and leave out the fiberglass.
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Beam calculations are not that hard for design engineers, what is hard is to predict the loads that can be experienced. Wharram way oversized his crossbeams, but he had his reasons. I think he may have gone to the 3X maximum load specification because he was no longer thinking about the loads on the floating catamaran, but the loads of a catamaran with one hull flooded.
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Down in Florida, a fellow named Boatsmith is recreating the Wharram Classic using inert fiberglass and resin with foam core. His crossbeams are glass. They can be quickly made in a simple mold and are very strong. Another quality is resilient flexibility like the fiberglass pole vaulting poles of years ago. The scantlings should be about ½ “ thick. Engineering composites gets very interesting, especially if some carbon fiber is used here and there. This would not be a bad choice for the replacement beam, but it would be an odd beam in this boat, one that was out of place, not flexing quite the same as the others.
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Another option would be aluminum. The short mast support beam in the middle of the boat was replaced with an aluminum beam. It was difficult to match that beam to the existing beam profile and bolt holes for the cross deck structure. Also, replacing the main beams would cost at least 3X the price of the original wood beams.
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Another aspect to the Wharram crossbeams is what an engineer would say is waste of materials, bad design. Why use these balk of wood crossbeams that serve no other purpose than to keep the hulls connected and in line, when the same amount of wood could be used for a deck cabin that would do all that and additionally provide some useful living space. Wharram himself added little deck cabins he called “deck pods”. His pods weren't structural members and relied on the crossbeams to support them. It is not an elegant design. I think someday a design that incorporates the deck pods and crossbeams into an integrated structure will evolve. These podbeams could be used the same way as the crossbeams, lash them to the hulls, preserve the flexibility of the design, and provide useful livable space in the design.
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For now, we will make the wood crossbeams. The wood will be pressure treated softwood, Kiln Dried After Treatment, that is stable and unwarped. I had some air nail fasteners, 18 GA stainless brads, but this project will use a lot. Like about 1,300. I ordered 2,000 from Home Depot online for free store delivery. I went to the store and picked up the wood. When I unloaded it at the dock I found it was not all the same grade. It was all Premium grade, but not all was Kiln Dried After Treatment. I could take it all back and go to another lumber company, a lot further, or air dry the pieces that were heavy and wet. I organized the lumber so that it was clamped and strapped to minimize warping, and let it air dry until we need it.
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The 18 GA brads came in, but they were not stainless. Another source was found online and 5,000 were ordered. I guessed they would arrive before the end of the project. Home Depot was emailed about their fraudulent product description. A shipment of epoxy came in, it would be enough for a couple of beam projects.
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Home Depot replied to the email and said “stainless steel” is a description of the finish! What a bunch of … There is no such thing as a “stainless steel finish” description for air nail brads. Plus, these Bostich nails actually had a brown stain finish.
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The crossbeam to be removed has the engine box and cross deck bolted to it. These bolts will of course have to be removed and some other support for the deck structure put in temporarily. The space was measured and a 10 ft length of steel pipe would fit. Unfortunately, while test fitting the pipe, it slipped down into the murky waters of Bodkin Inlet. Fortunately, I have a magnet on a string that is very strong and it actually attached to the pipe and it was retrieved, although very muddy.
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The pipe was hoisted by the running backstay winches which are conveniently located right above the beam troughs. The troughs were full of debris that had accumulated there, so it was all flushed out. This beam is held in place by U-shaped straps, two on each hull. They are located close to the gunwales. Instead of a beam strap like the Tornado catamaran has, which is a strap over the top of the beam and bolted to a saddle that holds the beam, this U-shaped strap is under the beam and extending up the front and rear face of the beam. At the top of the beam the U has “serifs”, one going foreward and one going aft. These are mounting tabs for a cap that fits over the top of the beam. There are 3 bolts through the cap into each tab. In this way the beam is totally encircled by the strap and its cap. The actual mounting to the hull is by huge bolts that are embedded in the bottom of the beam trough. Each strap has a bolt fore and aft that passes through a heavy tab that is welded near the base of the strap. Rubber pads are stacked on the huge bolts below and above the tabs and a plate is compressed down onto the stack with a securing nut. I think these are 7/8” bolts. The idea was the beams would be floating on these rubber pads, but under enough compression to limit their movement. In actual use there is no perceptible movement.
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There is fascinating information on the Polynesian Voyaging Society's web page. Unfortunately, some of the information about the catamaran “Hawaii'loa” has been left adrift. There is much more, however, and our present concern is crossbeams and beam mounting to the hulls. How they did it in the old days without modern tools and materials shows both invention and evolution, in a time when there was no written knowledge, when the canoe builders relied on ancient chants and the advice of the experienced “kahunas”. The basic scheme of beam mounting of the ancient canoes is the beams rest on saddles built into the gunwales of the canoe. The beams are lashed to something below, like a thwart. The lashings are intricately woven in a complicated pattern. The reason for so many strands and layers of lashing, the cordage in those days was not like modern synthetic ropes, so a lot more had to be used to equal the strength.
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The picture is of the beam mountings. Looking toward the starboard end of the beam we see the mainsheet traveler, which in total is 18 feet long, running along the top of the beam. At the end we see the cap bolted onto the U-strap with six now rusty bolts. A design flaw in these beam straps had soft galvanized bolts holding the caps together. These were replaced with stage 10 aircraft bolts with much higher strength and anti-corrosion coating. They will have to be replaced again. Below the cap we can see the U-strap extending down around the beam and a heavy weldment which is part of a right angle tab that extends into the dark stack of rubber pads. On top of the pads is a metal cap held in place by a huge nut. On the left we can see some dark splotches marking the edge of the beam trough cover which of course has been removed. The splotches are a urethane adhesive named UV6800 and are still stuck in place. This adhesive tends to lose its adhesion over time, but is generally equivalent to Marine Goop. In the foreground there are some cracks in the fiberglass coating on top of the beam. This is the result of moisture in the beam causing the wood to swell and crack the fiberglass. Under the mainsheet track are some white spacers which equal the thickness of the mounting straps, so the whole track is straight from end to end. The black stuff under the spacers is epoxy filled with graphite which provides strength in the bolt sockets and still allow the bolts to be removed.
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