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Friday, July 28, 2017

Preparing for the bow thruster install

The past couple of months of boat work have been focused on doing the design and prep work to install a bow thruster at our next haul-out. I have been driving boats of all different types and for over 20 years now and consider myself a pretty decent boat handler. Kama Hele is a very predictable, easy handling boat for a single screw, having a full deep keel, big rudder, and a 3.5:1 reduction gear turning a big prop.

But... there is no doubt that being able to spin the boat in her own length in a narrow fairway in an unfamiliar marina, or holding the bow tight to the dock against the wind while sorting out what we can tie off to would be a benefit when cruising. Of course we could have installed one for a lot less money and headaches while we were designing and building the boat, but I remember being completely out of funds when that time came and went. So, now the effort will require a lot of additional engineering and surgery on the boat to make it happen. So it goes...

We chose to go with a big, heavy, high-powered hydraulic bow thruster because our boat is also big and heavy, and there is no sense in going to all this trouble for a marginally performing installation.
After a lot of shopping we chose a 12" dual prop counter-rotating design by ABT (American Bow Thruster,
aka TRAC/Arcturus Marine). They are located in Rohnert Park (local) and do almost all of their fabrication work in-house. Excellent design and build quality from everything I've seen out there.
Here are some pics of the prep work on the hydraulic tunnel (12" sch40 steel pipe) and the fit-up of the gear leg and hydraulic motor for the thruster. We plan on welding this tunnel in place at our next haul out later this summer.

The engine PTO (power take-off) has been the most challenging part of the project so far. In order to provide the flow rate necessary to power this monster bow thruster (close to 25 gpm at low engine rpm) during docking, I had to upgrade the little 8gpm gear pump that we installed for the anchor winch to a 100cc axial piston variable output pump. This can pull hp in the 20+ hp range from the engine so the only option for driving it was off the front crankshaft of our Cummins 6BT main engine.

Even though the pump output is based on demand (it will happily spin at no load when no power is being demanded of the hydraulic loads attached to it), I really wanted the ability to clutch out the hydraulics completely when I'm not using the system. It was a big challenge to fit up: crankshaft adaptor-torsional coupling(to absorb vibration)-spline drive-BIG electric clutch-SAE C mounting pad-BIG hydraulic pump, and hang it all off the front of the engine in the limited space available. This involved some modifications to the front engine mounts and the framing for the deck plate in front of the engine.

Here is the result, which I am very happy with so far:

The big hydraulic pump just fit...

This pump also required up sizing the hydraulic tank. Pretty much the same deign as my old tank, but with a 12 gal capacity and up-sized fittings, including a 2.5" supply port to feed the new hydraulic pump. I am hoping that with the ability to clutch out the hydraulic system completely when not in use, I will be able to dispense with the complication of a cooling circuit for the hydraulic oil.

Since the new pump blocked access to the electic bilge pump in the bilge below, I moved the bilge pump off center, to the outboard side of the port side engine rail support. This puts it a little higher in the bilge, but it will kick in before any fluids in the bilge would reach the engine or the gear, so I can live with that.

This is all a lot of work, which hopefully will result in a high capacity robust hydraulic system that is big enough to also drive additional deck winches, pumps, and any other hydraulic gadgets we can come up with.

Monday, May 29, 2017

Dickinson Bulkhead Mounted Stove

This was definitely one of the biggest bang-for-the buck-projects we've done in a while.
We installed a Hurricane diesel-fired hydronic system when we built the boat and that is still running great, keeping the entire boat warm and dry in the winter and providing hot water on demand year-round. Hydronic is very efficient but lacks a certain charm that we felt you can only get from open flame radiant heat sources. To this end, we installed a Dickinson Newport diesel wall mounted stove in the little sitting area forward of the galley. The hardest part of the job was cutting a big hole in the 1/4" steel deck and fabricating /installing the stovepipe. I didn't want to remove a bunch of interior for torching out the opening, so I went with a hole saw (and lots of cutting oil). This stack has to be done right, with proper air gaps and insulation for the pipe, and proper length with as few bends as possible. We were fortunate to have a clear path straight up through the deck, while maintaining the recommended stack height. I made a stainless adapter ring for our compound cambered foredeck from 304 stainless. This provides a flat pad for the top fitting on the stove pipe to attach to.We initially used a straight rain cap but quickly learned that the H-cap is much better at preventing backdrafts so that is what we have on deck now. The barometric damper option that we bought with the stovepipe parts from Dickinson also assists in keeping a good strong draft up the pipe. The fire box and stovepipe create quite a bit of radiant heat, so some attention has to be paid to shielding inside the boat. We mounted the heater on a stainless plate held out a couple of inches from the bulkhead. We also mounted a similarly designed heat shield behind the stovepipe. Both heat shields have an airspace behind them and are open at the top and bottom. This creates a kind of chimney effect that carries hot air away from the bulkhead behind the heat shields. Seems to work pretty well. The fuel hook up was easy due to the fact that the elevation of our day tank in the engine room will gravity feed to the stove nicely down to about 25% tank level. This means no fuel pump needed. We run the built in fan on the heater for a few minutes at start up to get the draft going, then the fan goes off and all you hear is the light sizzle of the flame. Very nice.


Finishing the Shower

So the shower is pretty much done. Glass ordering and installation was about as tricky as I anticipated. Only one right angle to work with on the shower opening, otherwise all custom cuts. You only get one shot when ordering heavy duty tempered shower glass, so we spent a lot of time measuring and figuring out the best way to relate what we needed to the glass supplier. The fit-up was decent, but I ended up cutting out and resetting a couple of the shower sill tiles that stood a little proud from the others in order to get a nice tight gap all the way around. The gap is critical for a frame-less enclosure that doesn't leak. Overall happy with the results. All that's left is a way to latch the door in the closed position for cruising, and fabricating a rail for the little triangular shelf behind the shower pipe:

Saturday, March 4, 2017

Aft Cabin Shower

Picking up where we left off with the shower install...

We decided to go with flat sliced river stones for the shower pan and top of the bench.
After looking at a lot of options, we decided on 1/4" thick
12 x 12 gauged black Vermont slate tile for the rest of the shower.

Gauged means that the tile is finished to a fairly uniform thickness and exterior dimension, which makes for an easier install, and a little less rustic look compared to the chunkier standard slate tile which has a lot more variation in the individual tile dimensions. We found these tiles to be fairly lightweight compared to other options, and we really like the natural look.

Lots of steps in the process:
Finish frame out and seal all seams in plywood paneling
Fabricate and install shower drain assembly and plumbing
Install shower supply plumbing
Fiberglass the entire interior of shower stall
Install the pre-sloped mortar bed for the shower pan
Layup additional fiberglass layer over the mortar bed shower pan
with overlap to weep holes in drain assembly(this will drain off any moisture that gets under the tiles)
Lay in the river rock shower pan and bench top, grout, and seal
Install slate tiles on shower walls, grout, and seal
Install mixer and shower pipe assembly

Still left to do is to decide on a shower glass enclosure and door, make templates, order the pieces, and do the glass install.

Here's some pics: