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Saturday, December 5, 2015

The Skiff

Found this neat little fiberglass "lapstrake" Whitehall style rowing/sailing skiff a while back on Craigslist. The boat came with trailer, sail rig, oars, and a cover. The fore and aft interior "bulkheads" on the skiff line up perfectly with the davit system that we installed on KamaHele, which was what kind of drew me to this boat despite the slightly rough overall condition. The hull is 11.5 ft long which is just a little shorter than the width of our transom, so there will be no overhang when she is hanging from the transom davits. Based on the amount of built in floatation (the molded shelf running around the interior of the hull) she should stay buoyant even when swamped. I think the boat is early 90s vintage- maybe originally a kit put together by someone with just enough boat knowledge to be dangerous. Of course this is a bit of a fixer upper so I've been working on her "restoration" for the past couple of months. The basic shell was pretty good, but the rest of the fit and finish needed some work:

We started with stripping the boat of all trim and hardware:

Gunnels were re-fastened using copper hardware, and some of the other damaged or poorly installed trim work was fixed and re-installed:

The interior was cleaned up and bad fiberglass work repaired. I also re-enforced the fiberglass lay up where the four lifting points are going and added dry storage compartments fore and aft:

The interior was faired-out a bit, primed, and painted with two coats of single-part polyurethane:

Bottom was cleaned, and primed with two part epoxy paint.
For the finish on the hull, I used a two part polyurethane top coat. Very durable stuff.

I'm not sure that we are going to use any kind of anti-fouling paint on the bottom since the boat is going to be stowed hanging from the transom davits whenever she is not being used:

Next up will be installing the rest of the hardware and fabricating lifting rigging to work with the transom davits.

Tuesday, September 22, 2015

Transom Davits

Here's some pics of fabrication of our transom davit. This design concept has been kicking around in my head since we welded on the hinge pad eyes on the transom during the construction of the hull many years ago. The geometry is such that, when in the stowed (up) position, the dinghy is carried up above the swim step with enough clearance to walk down the steps and stand on the swim step with plenty of headroom. When lowered, the davits swing the dinghy out and over the aft railing and swim step and launch it in the water behind the swim step. If everything works out right with the rigging from the davit to the dinghy, this should not require block and tackle to launch or retrieve the dinghy- just lower it into the water until its floating, then unclip the lifting harness. We'll see how that works out when we get a dinghy to work with.

The first few pictures show some of the full size mock-ups and fancy drafting I did to get the measurements and geometry dialed in:

Next up was the fabrication and welding. I made the assembly in three pieces (two davit arms, and the bolt on cross support structure). This turned out to be a good move as this thing would have been really hard to handle and install as one piece. Here's my fabrication work before handing it off for final welding:

Some more fine MIG welding Romero's Welding at Mare Island:

Installation took some acrobatics, but it went together pretty much as planned:

Raising and lowering is accomplished manually with a hand winch rated at 1000 lbs and equipped with 7x19 stainless wire rope. The winch has an automatic brake and will hold the load whenever you stop cranking up or down. I will be adding some kind of safety locking pin mechanism to each arm at some point so the davit isn't relying on the winch brake to carry the load when up in the stowed position. The boom lift can also be used as a back-up to raise and lower the whole setup in case the winch system ever fails:

I rated the entire rig for a minimum safe working load of 1000 lbs (or better).  I figure the davit assembly weighs about 150, so that leaves us plenty of capacity for a modest skiff. We will likely go with a fiberglass rowing tender. I like the more traditional look- and they can be sailed, or motored with a small outboard. The plan is to have the dinghy set up to be lashed down on the aft deck behind the wheelhouse if we are doing any major open water crossings. Otherwise I feel pretty confident that the davit system is high enough and strong enough to do the job of carrying our tender, and will make launching and retrieving very quick and easy.

Tuesday, August 18, 2015

Solar Panels

Solar panels are installed and making electricity. The past few weeks has been a crash course in solar power technology. We ended up with six Kyocera panels for a total of 840 watts. We went with Blue Sky MPPT controllers for their compact size and excellent efficiency. With solar panels, shading is the enemy as it will reduce the output of other panels that are in the same circuit. To provide some isolation (which minimizes shading on one panel from affecting the rest of the array) we wired the panels in parallel, with home runs from each panel down to the controllers. We put three panels on each controller to further isolate the effects of shading on the overall output and to provide some redundancy. Each panel is fused before the controllers and the output of each controller is fused where it meets the positive bus of the house battery bank. This was a lot of wiring and took most of a three day weekend to finish. With everything online, we have been able to pull 50 amps out of the array at 14.2 volts during the day with clear skies. It could probably go a little higher if the house batteries a little less charged up. We had to turn on a lot of electrical stuff to get the controllers to see enough demand to get the output up to 50 amps. Our target for the rooftop array was 50-60 amps max output so we are pretty close to our expectations. We have been "off the grid" for three days now, with daytime solar charging seeming to keep up with our 24 hour demands. Each afternoon, our "state of charge" for the house batteries is back up to 100%. The nice summer weather and long days have helped. We are still using the shore power for the electric element in the water heater but when cruising, our domestic hot water can be heated on demand with the diesel burner that provides our hydronic heating circuit or via the heat exchanger with the engine coolant when we are underway. Everything else is running off the 12 volt house bank (refrigeration, lights, pumps, etc.) or using the AC output of the inverter (misc appliances, home depot freezer, and some electronics) which is fed by the same house battery bank. I think that a couple of more panels (maybe on top of the aft dinghy davits when we get those built) will give us a very solid solar power set-up to meet most of our demands most of the year. A wind generator would be a nice add-on too. Of course the beauty of solar is no moving parts and little to no maintenance.