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Tuesday, October 30, 2007
Yes, it is still too early to make decisions on this, but I have been following this topic for over a year now. Judging by the web, not much more has been made available by manufacturers of D/E propulsion. Of the stuff I have seen, I really like the concept behind the OSSA powerlite systems. Their approach says that more benefits are realized when you consider D/E propulsion as just a part of an integrated power system. Anyway, they have a promotional video that I thought was informative and not much over-hype.
Monday, October 22, 2007
Got the battery box roughed together and fitted. These will be the main house battery bank. The battery box will be in the forward center compartment under the main salon floor in place of a fresh water tank normally designed by the factory. There is still some room underneath the battery box for a smaller water tank (roughly 30 gallons).
The box itself can fit up to fourteen 6 volt standard "golf cart" style batteries. There is also room to squeeze in the "taller" golf cart batteries like the Trojan T-145's. The box was constructed of Coosa. The joints were glued and screwed. When finished, it will get a layer of glass over the inside bottom and halfway up the sides to give the box strength and seal the bottom to contain any electrolyte spillage.
As for the battery compartment, there are crossmembers supporting the bottom made from 3/16 inch fiberglass angle stock, doubled up (the green supports shown in the picture).
The box dimensions are flush with the inside walls of the compartment. For further support there will be a series of thru-bolts around the walls of the box, fastening it to the walls of the compartment.
Finally, there are similar crossmember beams spanning the top of the box to support the floor, Together, with their joints running along the side, will help hold down the box and the lid.
My estimations say this should be enough to support the up-to-1000 lbs of batteries.
The lower and upper supports for the box and the floor in this area are all held together by a system of machine screws and bolts. Therefore, should there ever be a need to remove the box and/or get at the tank below, things can be removed without cutting to gain access.
Thursday, October 18, 2007
Here are some shots of the template fittings for the forward bulkheads. I originally had hull curvature measurements in CAD at the corresponding points along the centerline. Simply printout full scale, overlay on a sheet of doorskin and cut the edges. Inside the boat, take a jigsaw and tweak trim the edges to get a nice fit.
The templates were hung in place in the boat to get a spatial feel as to how things will be and test assumptions that were made in the CAD and 3D drawings. So now we have something physical to reference to work out final design tweaks and changes.
The good news is that we have jsut enough room for "pocket doors" between the forward salon and the forward head as well as between the v-berth and forward head (room for such doors wasn't clear from the CAD drawings). Pocket doors meaning the type that slide and "disappear" inside the bulkhead rather than "swinging out" like a normal hinged door. Problem with swinging doors is that things get in the way of the path of the door and knock into things.
We have room for a 24-inch wide door between the fwd salon/fwd head, and a 20-inch wide door between the fwd head/v-berth.
Wednesday, October 17, 2007
So I got the Westsail's rudder bearing housing glued in permanently. Picture here shows it in place with the bearing and cap removed for illustration. The housing has sideways and aft reinforcement along the axes of the rudder post. Those reinforcing webs are 1/4 inch G10 fiberglass sheet, doubled to 1/2 inch. It is the same material as the bearing housing (just a different color). The G10 sheet stock is really tough (it is actually FR10, a fire resistant version of G10). A 36 grit green grinding pad barely scratched it up. The pad would wear out and start smoking from the friction before I could get some good tooth on those pieces. The final installation will see fiberglass and epoxy further attaching the housing to the hull in a method that will help spread side-loading forces from the rudder, to the hull. As mentioned before, the bearing housing is designed such that, should the bearing ever need replacement (hopefully never), removing it would only require cutting the cap off (thereby destroying it) and sliding the bearing out. A new cap will need to replace the old one.
Monday, October 01, 2007
While we wait for the paint to set up on the small boat, I am finding time to get back to Westsail projects. Forward Salon Floors With the final descision made on floor height in the forward salon, the floor pads can be glassed in. I did the final shaping of the foam and glassed them to the side of the hull. I had just enough resin left in my last 5 gallon bucket for the job. As before, the pads are structural foam (Airex C70) triangular wedges with one side shaped to the curvature of the hull to give a nice flat and level 90 angle on the opposite surfaces. The 90 corner is given a large round-over so the glass will stick to it nicely. CoreBond is used to stick the foam to the hull (and fill gaps) and three layers of glass are laid over the foam onto the hull. Staggered about two or three inches. Working with CoreBond is a little tricky. Its primary purpose is to bond foam coring materials to fiberglass (as is often the case when building a cored boat). It is a two part material (catalyzed with MEKP, just as the resin) that has the consistency of a light putty. It is lightweight and has very good resistance to sagging or running. This is important when bedding the foam pieces in place because you dont want them to shift when you turn your back. The CoreBond holds them in place just nicely. Then you can use putty knifes, toothed squeegees, trowels and tounge depressors to help shape the CoreBond that "smooshes out" to fair and fill gaps. Once in place, laying the wet fiberglass over the wet CoreBond will enable you to smooth out any bumps and troughs and achieve a chemical bond between the two. The trick comes in that the CoreBond tends to set up faster than the glass resin, and, it is not very easy to gauge the amount of catalyzst to use on the CoreBond (the MEKP catalyst comes as a dark green thick putty). So, you must not overwork the CoreBond and work faster with the glass if you want that chemical bond. So, this is the LAST of the permanent installation of the floors. Except the engine room and hallway. Those are being saved for last, as, the cockpit floor will be used to move large parts/pieces into the boat, and, therefore, will be the last area of the boat to get floors and walls.