Sunday, July 23, 2017

Hydraulic system

Two things happened while on our recent

trip to Key West that kicked me into gear in regards to finishing the hydraulic system that I never really started. The first thing that happened was having us get pinned against a piling due to high wind while trying to get into our slip at A@ B marina. The second thing that happened was being anchored in Key West for our last night in 25kt winds and stressing over having too small of an anchor due to us not having the hydraulic anchor winch working, making it necessary to use too small of an anchor since we were hauling the anchor by hand.

The hydraulic system powers the hydraulic bow thruster and the hydraulic winch. The system is powered by a load sensing variable displacement pump that is driven by a live PTO straight off of the transmission shaft. Live PTO means that the pump is always turning as long as the main engine is running.

Having said I never really started this job, is true in some regard. The bow thruster has been purchased and was installed. The pump and solenoid valves had been purchased as was the hydraulic anchor winch. This was the one of the most challenging jobs I've yet to do on this the boat build, and like everything else boat building, this project took about five times more effort and funds than I had imagined.

The first step in getting this job rolling was measuring the hydraulic lines that would go from the engine room to the anchor winch and bow thruster. My first route of choice was down the port side of the boat through the master cabin and behind the shower. As I pulled the chase covers away, I soon realized I had not left myself enough room to route the four 3/4" hoses behind the shower wall. The only other option was overhead down the center of the main cabin, or down the starboard side via the identical chase as the port side. The starboard was the most viable route so now I had to make it so. Measuring the lines was a matter of using garden hose pulled through the route. After an afternoon spent pulling and routing the garden hose, I settled on a measurement of 50' for all four lines. The main difference between hydraulic line and garden hose is how much stiffer hydraulic line is thus much harder to route. It turned out that two of the lines worked out perfect being 50', but the other two came up 4' short, and needed hose added to them to make it work.

Having a length on the four main hose was a good start, but didn't even scratch the surface on how much work was still ahead of me. The next step was to get all the system parts mounted and plumb the hard pipe parts of the reservoir. The reservoir has a 2" suction line feeding the pump, and a 3/4" return line which passes through a filter. I installed valves on both the suction and return line. Once the reservoir hard piping was done, I could begin the process of identifying the myriad of fittings I would need along with measuring and sizing all the connecting lines. There is a method to the madness in that one has to be versed regarding the fitting types, sizes, and how to measure a hydraulic line. Time is the constant here, and it was amazing just how much time I had in staring at my work area trying to get a vision of how all these parts and hoses were going to be installed in a way that looked professional....time seemed to vanish as I painstakingly identified fittings, hose size and length, fitting orientation, and then putting this on a material check list. More time was spent transferring the checklist to and order and double checking that all was correct and nothing was missed or double ordered ( which is was ).  Once my order was placed and paid for, more time passed as I waited for the order to make it's way from Pennsylvania to Cape Coral.

When I first began this job, I had every intention of using the local hydraulic shop to purchase all my lines and fittings. The business model of these local hydraulic shops is that when a hydraulic component on a machine fails, 99 times out of 100, the customer walks in and needs the part immediately.  The hydraulic shop knows this, and prices their work accordingly. I gave the local shops an opportunity to quote what I needed, but they could not come close to what I could get the material for online. Why would a local shop sell me their product at $.30 on the dollar when they could use their assets and product to sell to the non stop traffic of local contractors needing parts immediately and willing to pay for that service? It is for this reason I shopped online at   Discount Hydraulic Hose , and could not be more happy with the quality and speed of service they provided. On at least two occasions, they called me directly to give me choices of parts due to availability in order to make sure my orders shipped the same day.  Discount Hydraulic Hose prices are what I would consider  reasonable, and because of this I tended to over order fittings as it is cheaper in my opinion to have two too many vs being short one.

The basic flow of this system is the engine driven hydraulic pump gets fluid from the 12 gallon reservoir through a 2" suction line. The pump is always in motion as it's powered by a live PTO. The pump supplies pressure to a distribution manifold via a 1" line. Using a distribution manifold vs "T's" in my opinion makes for a neater job, and gives me the ability to easily expand the system. From the distribution manifold, pressure goes through a block where the two electrically controlled solenoid valves are mounted. The solenoid valves control the bow thruster circuit, and the anchor winch circuit. If either circuit does not need power, the oil returns to the reservoir through a cooler and filter, and begins the loop again.

The variable displacement load sensing pump is able to provide full power while the engine is operating at idle speed. This pump is controlled by a hydraulic pilot circuit which tells the pump it needs to power up to it's full pressure of 2500 psi with a flow of 10 gpm. Basically, when the engine is running the pump is at idle and only puts out 500 psi. As soon as we need to use either the winch or the thruster, the pilot circuit is engaged, and the pump powers up to 2500 psi. Once either device is not requiring full pressure or flow, the pilot circuit shuts down, and the pump returns back to it's 500 psi idle. Operating the pump in this manner is by design and provides longevity and helps control heat.

The oil is cooled via a 2" x 9" pipe in a pipe cooler which is tapped into the main engine keel cooler circuit. The cooler was sized in the original design.  As you might recall from an earlier post, I had to add an electric pump to the transmission cooling circuit and it's within this line of the circuit that I tapped into to cool the hydraulic oil. The hydraulic oil temperature is holding steady at 160 degrees, which is within the designers specs, but is on the high end. I think I have noticed a slight increase in engine room temperature as on our last long passage of 22 hours, the engine room temperature seemed to hold steady at 112 degrees ( it's summer here, and the outside air temperature on that passage was 94 degrees ). Looking at past logs of our trips, the ER seemed to operate between 108 and 110. The steering oil is keel cooled on it's own circuit and always shows an operating temperature of 105 degrees. The transmission temperature holds steady at 140 degrees, but it has a larger 2" cooler with a length of 18". I'm seriously considering, on the next haul out, of adding a keel cooler for the hydraulic system, and possibly the transmission too. Adding two keel coolers would be job, but would eliminate the electric pump ( which I have confidence in ), keep the oil cooler, would eliminate a source of engine room heat, and would make the boat that much more reliable and trouble free.

I do have one issue that might need to be corrected on the system. When I ordered the solenoid valves and their distribution block, I didn't have a clue as to what I was doing. The block I have now does not provide flow to the pilot circuit, so the pump has no way to switch between idle and full pressure/flow. The block that is installed only provides flow to the solenoid valves along with return to the reservoir. What needs to happen is when the solenoid valves open, the block should provide pressure to the pilot circuit turning on the pump, and when the valves close, the block should dump pressure back to the tank thus turning off the pilot circuit. The way I dealt with this problem was to add a solenoid valve to turn on the pilot circuit. When I need to operate either the anchor winch or thruster, I turn on the pilot circuit via a switch at the helm which powers up the pump, and when we're finished with either device, the pilot circuit is turned off, which puts the pump back to it's idle pressure of 500 psi.

The result of all this is that we now have a bow thruster that works fantastic as well as an anchor winch that can handle a proper size  anchor for our boat.

The thruster is made by Key Power, and is a 10" size. The thruster has a hydraulic motor on it which turns a gear box. The gear box uses 90 weigh oil, which I modified slightly. The problem I saw with the gear box ( which might not have been a problem ) is it was not vented. I talked to the manufacturer, and they suggested installing a header tank using one of the fill ports, and some clear tubing to connect with. Adding a header tank was simple as I used a gravity paint gun's paint pot for the tank ( all pipe thread, and $9.00 ). Installing the header tank in the blanket chest keeps it out of the way and makes it as simple as looking at the clear tube to make sure there is oil in the case. The problem with not having a vented case is the risk of blowing the seal between the thruster prop and the gear box. If that seal fails, sea water will get into the gear box and possibly the boat. The thruster is in a water tight compartment, and while it made installing the lines a challenge, it was worth the trouble for the peace of mind that compartment provides.  The  horse power rating of the thruster is 15, and it's obscene how much water this thing shoots out it's tube. We've only had to use the thruster half a dozen times, but I'm extremely happy about how much it moves the boat, and how much easier it makes docking the boat. Being a single screw boat with a lot of windage, my stress level is way down as the boat is now a dream to handle.

The anchor winch we have is made by Kinematic, and is primarily used in the commercial fishing boat industry. It's a drum winch and for sure has a commercial look to it ( which I like ). I was able to get 300' of 3/4" line and 20' of 3/8 chain on to the drum. Because we'd been hauling the anchor by hand, we have been using a 30 lbs Danforth anchor. The Danforth has done me well for 20 years, and I'm for sure not going to bad mouth it as we've anchored 100's of times with it. I will say since we've moved to an area where tide switching has to be considered we've dragged twice with the Danforth due to the rode catching on the fluke bar and fowling the anchor. Now that the anchor winch is fully operational, I decided to upgrade our anchor to a Manson Supreme. The Manson sizing chart had us being able to use their 65 lbs model. Defender was having a sale on Manson anchors, and was sold out of the 65 lbs model, but had the 85 lbs anchor for about the same money, so the 85 lbs unit is the size I chose. After a few times anchoring, I can say how happy I am with how fast the Manson sets, and how well it seems to stay set. I can also for sure say the kids love the anchor winch as they no longer have to hoist by hand.

As I said above, this was one of the most challenging jobs I've done to the boat to date. Hydraulics are for sure expensive to install, but the reliability and longevity of the system is second to none. Being in a large harbor, with lots of transients coming and going, I've seen at least two occasions where captains have exhausted their electric thruster batteries trying to maneuver in strong winds. With the hydraulic thruster, and hydraulic anchor winch, we'll never have to worry about running out of power. The reliability and robustness of this system is unmatched.

The last major job on the boat is going to be installing the air conditioner for the salon and wheel house. The duct work is all in place, but the unit has to be purchased and installed. Another project I want to get installed is and inverter so we can have the fridge running without running the generator. Once  these two projects get completed, I might have to think about changing the name from Conall's Boat Build to something else.

Cheers   

 

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