We are adding a few electric bits to the flying bridge, each of which demands its own inventory of copper and insulation. The result is a busy area under the deck, and wiring ducts to the flying bridge are now very full. Here Cory McMahon is waiting for one of the crew up top to pull another cable.
Cory has made a couple of temporary joints for testing with these 3M telephone industry connectors. Press the wires together within the fitting, and they are automatically sealed with silicone, after which they live happily underground–at least that is the theory. In our case, with testing completed we have soldered the connections, and then placed heat shrink over the joints.
You will no doubt recall Eric the Terrible, he of the fairing hammer working on our swim step extension last fall. Eric has mellowed and here he and another Bausch American top hand are working on a final version of the recently prototyped rowing dinghy support rack.
Cory has made up a Mark III underwater exhaust interceptor, version 3.1 and 3.2.
These have similar shapes, except that 3.1 has hard edges and 3.2 softened corners. They are shaped in foam which has been glued to a piece of fiberglass laminate, then covered with two layers of cloth soaked in epoxy. We think we are getting close. By Mark IV we should be ready to do a permanent interceptor.
Jeff is the Jarrette Bay manager, and has been kind enough to arrange for us to be launched on Saturday. Since the crew is off, we were placed in the slings Friday afternoon, and Jeff has volunteered to drive. He has indicated this is his first time driving a Travel Lift. Fair enough, as it is our first time driving a boat.
Why it is a good idea to inspect impellers after storage – we did not. After launching, while hanging in the slings, we always burp the packing glands, check the bilge for leaks in the engine room, and then start the engines. One of the disadvantages of underwater exhausts is that you cannot see water flow to check on the cooling water system. But we have clear (for now) feed lines and they showed flow. The water flow alarm on the port engine was sounding, but we assumed it was stuck. Then we noticed the engine temperature climbing and checked various items with the remote temperature sensing gun. The port engine raw water pump was very hot, so we anchored, pulled the port engine pump cover, and found the above. Next time we’ll listen to what the alarm is saying!
Being late on Saturday night and with a clean bunk in an organized interior beckoning, we shall leave the results of our first short run for a new post. Let us just say for now we are not disappointed.
Posted by Steve Dashew (June 9, 2012)
June 9th, 2012 at 11:45 pm
Steve,
How old was the impeller and how many hours of use had it endured ?
If your John Deere’s water pump is compatible with Speedseal , mine is not, I suggest checking it out. Their tests reveal both extended life of 3X in hours and run dry times of 10 minutes and longer – repeatedly !
June 10th, 2012 at 8:09 pm
Howdy Ben:
The impeller has 845 hours on it and was a year old. We are waiting for an order of Globe impellers to test. Otherwise, this impeller would have been replaced on a preventative basis prior to launching.
June 10th, 2012 at 5:07 am
What is an exhaust interceptor?
thanks…
June 10th, 2012 at 8:16 pm
A ramp ahead of the underwater exhaust to relieve back pressure by creating a bit of negative pressure from the flow of the water.
June 10th, 2012 at 8:46 am
Hi Steve,
Back in 1979 I had the good fortune of having as neighbor on the “Friendly Canal” in Fort Lauderdale Captain George Swinnerton, on Pierre DuPont’s yacht Barlovento II. On the way to the Saturday morning flea-market Skippy said to me that having a strainer downstream of the raw water pump is an excellent way of preventing impeller bits from clogging the heat exchanger, but more importantly, spotting the first bits in the strainer on regular inspection tour and start-up. I found that one inch strainer that very morning for $5, and it has been doing superb duty ever since.
BTW, one or two heat-sensors immediately downstream of the raw-water return “T” is a very effective and inexpensive alternative to flow-meters.
Peter Hartmann
Ahaluna – 52′ Michel DeRidder sloop
June 10th, 2012 at 8:19 pm
Good ideas Peter:
We have heat alarms on the water injection elbows and are adding temp sensing probes to the N2K system on the theory that small changes in temperature are a good leading indicator of flow cooling water flow issues (be they impeller or strainer related).
June 10th, 2012 at 3:38 pm
Steve,
I’m interested in learning what you are doing with the rowing dink support rack. I understand you have a shortened version of Gig Harbor’s Whitehall.
Some questions for you.
How much did you shorten the Whitehall? How does it row in its shortened state? Do you also sail it, and if so, how does that work in the shorter version. Have you ever used a small outboard on the shorter Whitehall, and, how does that work?
Can you give details on what you’re doing with the rack and how you’ll mount the dink when you’re underway, please. Will the rack be in the way when the dink is in the water?
Many thanks,
Stedem
June 10th, 2012 at 8:27 pm
Hi Stedam:
Our Gig Harbor dink is full sized, but it is so fine aft that shortening would probably be a benefit. You could easily take 18″ out of it. We have a sailing rig, but have not used it enough and it has been moved to the garage. We do have a 2HP back up outboard, used when the grand kids are with us. It moves right along, but for everyday use an extension tiller would be a good idea. The rack is intended as permanent. we’ll have photos in a few days when completed. We are going to eventually make a mesh bag for the rack and store our stern anchor rode/towing warp/Galerider there. This keeps them handy to where they would be used and frees up space in the forepeak. The rack remains in place with the dinghy in the water, but is out of the traffic pattern. It is built so it is easily demounted, however.
June 12th, 2012 at 7:30 pm
My, oh, my,
Another failure of the raw water system. I’m the guy that you dismissed, who commented on the benefits of skin coolers and dry exhaust. Eventually, you’ll come around.
🙂
John
June 12th, 2012 at 8:55 pm
John:
There are benefits and drawbacks to both systems. We have lots of experience changing impellers and raw water pumps. It is a quick, easily accomplished job. Compared to the dirt, and noise of a dry system, not to mention the isolation issues with a dry exhaust, and condensation, we prefer raw water cooling.
June 16th, 2012 at 12:07 pm
Tony Athens of Seamar Marine believes that the raw water pump moves way more water than necessary to cool the exhaust and adding all that water to the exhaust increases backpressure. He T’s the hose to the exhaust elbow and directs some of the cooling water to a thru hull in the topside. This also allows a visual check that you’re actually pumping water, though you do actually have to look whereas a flow or temp sensor with buzzer would let you know automatically. On the plus side the T and thruhull has no moving parts or elec connections to worry about
June 17th, 2012 at 5:03 pm
My guess is the Deere engineers know what they are doing with water volume and exhaust, and in our case we typically upsize exhaust diameter anyway. On Wind Horse our hydraulic cooling heat exchangers are on an exhaust cooling water bypass circuit and provide a telltale.
That said, you probbly have a point in some situations. The major concern I would have is if you start to lose flow, the exhaust line might get cooked sooner than otherwise would be the case.
June 17th, 2012 at 1:20 pm
Hi Steve; interesting comment re not using the sail rig on your dinghy. We have discovered the same thing with ours. Rarely used, and the major benefit was to elicit comments of praise/jealousy from other boat owners in the anchorage…
A question about your experimental underwater exhaust system. With the ramp in place, I can see the advantage while moving forward, but what about in reverse? Would the ram effect cause a problem?
June 17th, 2012 at 5:14 pm
As long as the engine is running everything is fine. There is a possibility of having water forced up into the exhaust line of the dead engine, but have not experienced it yet (happly). The ramp itself is of such small proportions that it is doubful how much impact it would have at slow stern sterns.
Perhaps other SetSail visitors might have experience and will chime in?
June 18th, 2012 at 8:51 pm
I’ve been waiting to see how your solar panels have come along. Are you going to update us on that?
June 19th, 2012 at 1:11 am
Stay tuned. We fit them in forty eight hours!