Follow by Email

Sunday, August 27, 2017

More prep for new hydraulics and bow thruster install

Here are some pics of another weekend of work getting ready for the installation of the new bow thruster and hydraulic system upgrade. In order to get access to weld in the 12” pipe that will become the bow thruster tube, I had to remove some interior interferences in the forepeak. This mostly involved cutting back the decking in a way that would allow access for the work, but could be temporarily re-assembled so we don’t have to live with a big hole in the deck for the next few weeks.

In the engine room, I installed all the hydraulic distribution blocks and other components, including adjustable pressure and flow controls coming off the main pressure output of the pump for the anchor winch. This is so that the high 3000 psi pressure and 20+ gpm flow from the pump (as it is set up for the bow thruster) doesn’t overwhelm the winch motor or any other less demanding loads we attach to the system.

The system of distribution and return blocks make for a neat arrangement with minimum extra fittings, and lots of extra ports for future expansion. In order to fit everything on the bulkhead (including the big cabinet housing the electronics for the hydraulic system), I had to move the fixed fire suppression bottle over a few inches. All the mounted components and distribution blocks are attached to the bulkhead with bolts that are threaded into the aluminum mounting plate from the front, so they are easy to remove if needed.

A few additional hose runs from the engine room to the bow are needed for pressure, return, and case drain lines. New holes are now drilled through the bulkheads and once painted, I will be installing JIC hydraulic bulkhead fittings at these transitions.

 With all the primary pieces installed, I will be measuring (at least twice) and making up the hoses that connect everything together. Cleanliness is critical with hydraulic stuff, so I am doing my best to keep everything clean and capped during the install.

The only hose that does not use a crimped fitting is the supply line from the tank to the pump inlet. This is a monster 2.5” id hose. If they even make crimping dies in this size, we definitely do not have one in our shop. Instead, it will be secured will dual T-clamps at each end. Since this is a low pressure line, that should be more than enough to stay leak free. I was a little worried about fitting up this hose because in this size, the necessary wire reinforced construction to keep from collapsing under suction makes it very inflexible. Fortunately, with a straight flange adapter coming off the bottom of the pump it made a nice easy single curve down and straight back up to meet the tank fitting. Both the supply and case drain fittings at the bottom of the tank have ball valves that will be handy for servicing the system without draining the tank. I like to remove the handles on any valves that are normally open and would cause damage to equipment if accidentally closed when running, so I’m doing that here as well.

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: