Hydraulics


Delfin is almost entirely hydraulic.  Hydraulic equipment includes:
  • Maxwell 4000 forward windlass
  • Maxwell 2500 stern windlass
  • Trac stabilizers
  • Pacer de-watering pump
  • High Pressure washdown pump
  • Boom winches
  • Bow thruster
  • Stern thruster
The decision to go all hydraulic was in part driven by the reliability of such systems, relative ease of maintenance, and the size of the genset on the boat when purchased - a 20 kw North Lights.  This genset allowed for a redundant pumping source, and makes possible running both bow and stern thrusters simultaneously.  This system is admittedly a bit of overkill, but it is rather nice to be able to pivot in one's own length in a crowded marina, or dock by powering sideways. 

The primary pump is a Rexroth  A10VO 100 cc powered off the flywheel of the CAT 3306 via a drive shaft, with the auxilliary a Rexroth  A10VO 45 cc pump driven via the PTO output off the genset.  These pumps will deliver a combined flow of 317 liters per minute at max flow.  The point of the big pump on the CAT is to allow for reasonable flow at idle - at least enough for the bow thruster at 75% power.  Cooling of fluid is accomplished with a small hydraulic motor that circulates the fluid through the original half pipe keel coolers welded to the hull. 

In hindsight (always crystal clear), being able to operate the bow thruster off the CAT at idle became the dominant design driver resulting in a bigger system than is needed for normal use.  Will we be glad we have an 'overbuilt' system?  Probably, but I might scale the system down were I to do it again, and just start the genset when docking.  As it is, we can raise and lower bow and stern anchors whilst spinning in circles off the thrusters.  Pointless you say, but a great Youtube video.....

Maxwell anchors:  Work flawlessly.  The primary anchor is a 170# Bruce with 1/2" G4 chain, and the system handles it just fine.  One advantage of hydraulics is that one can run them continuously without causing any problems.  The main disadvantage of the Vertical Maxwell is the fact that the underdeck body of the windlass is cast aluminum, which appears to me to be about at sea water friendly as unpainted steel.  Because Delfin's anchors are in 'boxes' welded to the deck (see refit images section), this motor body is exposed to a salty atmosphere.  The result is that the aluminum bubbles, the paint falls off, etc. etc.  The solution was suggested by Sean Herron at Bracewell - lanolin spray.  Never having seen a sheep with rust or corrosion this was tried and once metal is sprayed with this product, corrosion seems to be a thing of the past.

Trac Stabilizers:  Wonderful piece of equipment.  We installed active stabilizers with 9 ft2 fins for presumed resale value, but as former sailors, we thought that stabilizers were only for people who get seasick.  No longer.  Can me soft, but being able to push a button and live life on a largely horizontal plane now seems a luxury like indoor plumbing.  The alternative works, but who wants to go back?

The Trac engineers are knowledgeable, and their support is nothing short of remarkable.  Frankly, I have never worked with a company more dedicated to just doing it right.  Highly recommended, although I admit I have no experience with alternative companies.

Pacer de-watering pump.  This unit is designed to allow us to pump 200 - 300 gpm overboard if we take a torpedo, or spray down a neighbor, or ourselves in the case of a fire.  This is accomplished via a Y valve shifting between 3 pickup points in the E/R, Master Suite and Forward Cabin and the raw water intake valve.  Since we haven't caught on fire nor taken any torpedoes we can't vouch for the effectiveness of the system, but it seems to work.

High pressure wash down pump.  I'd put hydraulics on a boat just to have this piece of equipment.  The ability to pump 3000 psi for quick cleaning is really a nice luxury.  We use this for cleaning the anchor chain off when we weigh anchor, and it has enough power that we can cut through seaweed clogs when needed.  Love it. 

One essential feature that was not thought about in installation that is mandatory is a flow switch to shut off the hydraulic pump when water isn't moving through the wand.  Without this, the system works, but you are relying on the bypass valve on the pump which just means the hydraulic fluid heats up way more than you want it to.

Boom winches.  See the 'Mast' link for details on how these winches are used, but PullMaster 2000# winches were installed.  These are commonplace on work boats, and perform day in and day out for years without problems.  On a dude boat like Delfin, they will certainly outlive us.  One disadvantage is that they are made of steel, and so must be painted to avoid rust.  At some point, we may tear them down and plate them, but for now, we'll just keep painting them every couple of years.

Trac thrusters.  Delfin uses a 12" prop for the bow and a 10" for the stern.  These work wonderfully well, and quietly.  Their relatively low sound level is a welcome contrast to electric alternatives, and they can work continuously without overheating.  We actually had an opportunity in 2008 to appreciate another advantage in being able to move sideways through the water.  In rounding the north end of Lopez Island in the U.S. San Juans, we saw what looked like a person clinging to a fender.  Moving closer, that was precisely the situation, and we were able to quickly sidle up to a 68 year old gentleman with a heart condition who had fallen off his son's boat while bringing in the fenders, unnoticed.  With water temperatures in the 50s, this person had about 2 minutes left to live after 10 minutes already in the water, and it was a good thing to be able to move up to him without maneuvering with the prop.  He was unable to do more than cling to the fender at this point, so if we hadn't been able to position the boat so that the gangway was right where we could grab him and drag him on board, the outcome might have been very unpleasant. He survived, by the way.