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Nothing on this website or in direct communications received from us, or in our articles in the media, should be construed to mean or imply that offshore voyaging is anything other than potentially hazardous. Dangers such as, but not limited to, extreme weather, cold, ice, lack of help or assistance, gear failure, grounding, and falling overboard could injure or kill you and wreck your boat. Decisions such as, but not limited to, heading offshore, where you go, and how you equip your boat, are yours and yours alone. The information on this web site is based on what has worked for the authors in the past, but that does not mean it will work for you, or that it is the best, or even a good way for you to do things.
Hi John,
I was not till I came to suggestion 13 that I realized how pertinent your article was to boat owners who do not have aluminum boats as there are a lot of aluminum masts and booms out there.
Alchemy was 2+ years old and a fresh water boat when I bought it and within a couple of years I had pulled all fixtures on the mast and had Duralac-ed or Never Seize-ed them. Some of them machine screws were already hard-ish to remove, even in that short period of with favorable conditions. I, of course, missed a few and at a later date (5-6 years later), they needed an impact driver activated with 3-pound sledge hammer to remove and most times the fastener was not re-usable.
I have since suggested to every new boat buyer I know to remove and TefGel (preferred now) all ss to aluminum connections ASAP. Interestingly, those owners who have done so and gotten back to me all report no dis-similar metals protection for the connections on these brand-new often high-end vessels.
Used boat owners should do the same. It would be an item I would check when buying a new boat. It would tell a number of things: the depth of maintenance for sure, but also, I would consider spars where the fixtures are un-removable with regular hand tools as damaged. I would direct a surveyor to check this and might try to parley this into a price reduction, especially if the spars are in need of painting or other immediate attention.
My best, Dick Stevenson, s/v Alchemy
It’s generally wise to assume that on anything aluminum that comes into your possession – whether new or used, and whether it’s a $10 or a $1,000,000 item – whomever last put it together will not have coated the fasteners properly. Even if it’s brand new, the guys who built it probably either don’t know why Tef-Gel is important, or it wasn’t in the spec, or they were in a rush and omitted it. Just budget the time to back them all out and coat them properly.
And I agree with Dick’s recommendation to try backing out fasteners that
thread into aluminum, and to consider the item damaged if they’re seized or corroding, before buying.
Aluminum is a great material, for many reasons. It just requires a different set of construction and maintenance rules than other materials do.
Hi Dick,
Very good suggestions, thank you. That said, I fear that the problem of dry threaded SS fastenings into aluminium is so common that anyone who takes on getting them all out on a boat more than a couple of years old would be taking on a task that could keep them at the wharf for a very long time, rather than cruising. Not sure what the answer is, except to keep beating on mast manufactures about this.
Hi John,
Agreed. I would not wish anyone to stay at the dock or the boatyard doing a non-essential job like that. That said, many PITA jobs lend themselves to being done out cruising as long as one borrows the head-set espoused by the Hippocratic Oath of “doing-no-harm”. There can be lots of “down time” where you can go after a few fasteners at a time. Another similar PITA job that can be done sporadically and pays big benefits down the road is doing wiring and plumbing schematics. For those who stop cruising for the winter, these projects can be excellent winter projects.
My best, Dick Stevenson, s/v Alchemy
Hi Dick,
That makes a lot of sense. I love the Hippocratic Oath parallel.
John
Having brought a 20 year old Ovni 2 years ago l am reading your articles with keen interest. You have confirmed one change l am about to do as the prop shaft bronze packing gland is earthed to the hull. Did not think that was correct so thanks for the very clear clarification.
Effendi did not have a leakage meter at time of purchased. After researching l ended up getting the SeaBis mainly because l could buy it locally in Australia. Yes the website is poor and vague. But unit works well and shows the slightest fault of which Effendi had several which l have solved. Still need to isolate the engine, windlass and bow thruster which all have negative leaks. Though these all have both postive and negative isolation switches when not in use so only a concern when in use.
In regards to isolating the engine. I have a Yanmar 4JH4-TE and the pressure and temp senders are single pin so negative is through the engine. I have contacted Yanmar and they don’t make 2 pin senders. As such any advise on isolating the engine with single pin senders
Thanks Chris
Hi Chris,
Good to hear that the SeaBis is a viable leak meter, thank you.
As to the isolation on the Yanmar, that’s a royal pain in the neck. The best course of action would be to replace the senders with two pin. I know that VDO makes them. Of course here the issue is going to be compatibility with your oil pressure and sea water temp gauges since there are no standards, at least that I have ever been able to find.
I think if I was faced with this I might take a big step and consider replacing the engine panel with one of the new NMEA electronic monitoring systems that will have a spec of what sensors to buy.
On the other hand, In theory, I think but am not certain, if you can totally isolate the engine from the hull the fact that the battery negative is connected to it should not matter since there would be no circuit. Still, if it were my boat, I would be a lot happier if I could get the engine truly isolated from the negative side.
Any thoughts, Matt?
John
I am thinking isolating the engine from the hull only works until you open the seacock as the salt water then completes a circuit. I have plastic seacocks which electrically isolate the engines raw water from the sea when closed. I see this as I have battery isolating switches from both positive and negative. When I close the engines negative switch I get a caution warning on the SeaBis. Then when I open the seacock the warning goes to critical. With the engine off, I can leave the seacock open and open the negative switch and the SeaBis returns to normal.
Thanks for the lead on the VDO senders. Looking in the Yanmar manual it appears they use VDO senders. So I am hoping if I can get the VDO PN off the senders then I should be able to get the 2 pin equivalent. I like the idea of having a negative bus. That would be the solution wiring the new negatives for the senders. Then instead of having a heavy-duty starter solenoid in the negative lead. I would put a battery isolating switch between the starter and the negative bus. I could then simply turn it off after starting. This is following the mantra of “keep it simple”. It seems a workable solution to me. Though what am I missing?
Chris
Hi Chris,
No, that’s not right. The fact that you are seeing a warning when you open the seacock shows that the engine is not in fact isolated from the hull. If it were there would be no circuit and no light on the SeaBis. The path through the water is only one side, it is not a circuit without something on the engine being connected to the hull. See #18 above.
One common place to for this to happen is the gear shift controls, but there are many other possibilities. The easiest way to trouble shoot is to do it with the boat on land and connect an ohm meter between the hull and the engine frame and then trouble shoot until you get infinity.
You need to get this sorted, otherwise any time the seacock is open you will be getting stray current corrosion.
Also, I would use a solenoid in the negative, not a switch: In an emergency when you need the engine right now, you don’t want to be going below to turn on a switch. Good quality solenoids are very reliable, so not a problem.
Hello Chris,
You might have there a mounting bracket where oil pressure switch and sender are installed, that is mounted on rubber pads and fed by a short hose – ie. pressure sensors are not necessarily directly screwed on engine block.
I was lucky to insulate one 6-cyl yanmar engine by just cutting the metal braid on oil hose, so that it didn’t earth the sensor mounting bracket anymore.
There was some reason why we had trouble sourcing suitable insulated pressure sensors, so that bracket insulation was necessary then. But 2-wire temp sensors were easy to find at the time.
Last thing to add was insulated alternator and earthing solenoid for starter motor, and Voilà – insulated Yanmarin.
We did use Bluesea ML 7701 heavy-duty thing for solenoid , but on hindsight, it was a bit overkill. Regular heavy-duty automotive solenoid would have been fine.
It seems that 2-wire pressure senders are readily available now. I cannot remember what was the problem on 2014, perhaps there was a temporary shortage.
Hi JCFlander,
Good suggestions on where to look for the hull short, thank you. And given that I regard being able to start the engine at a moments notice as one of the most important additions to safety we can have, I like your original choice of the Blue Sea solenoid over a cheaper automotive one.
John
I figured I was missing something, opening the seacock complete the other half of the circuit. I also see my logic of using a switch to isolate the starter is flawed. I was thinking that as I have to enter to cabin to turn on the negative switch I would also turn on the starter switch at the same time, then turn if off after starting. Though once I have isolated the engine from the hull I will be able to keep the engine positive and negative isolator switch on at all time while under way. So a big safety plus and a good reason to spend the time and money in isolating the engine. So thanks for helping me to clarify the logic. And thanks for the advice on trouble shooting on land. It is very timely as Effendi will be lifted out next week.
JCFlander
Thanks for the information on how you isolated and the source for senders. And I see they are in Australia so a bonus.
Chris
I’m a bit surprised that you got what I meant 🙂 I really need to wait before posting, I seem to have a tendency to encrypt myself with plain words… :d
Anyway, I managed to find two pictures of the thing:
– First: mounting bracket. And yes, this was Yanmar gray before blasting. From left to right, lo press switch, press sender, and starter solenoid (which is optional).
http://aijaa.com/pBLZdg
– Then, oil hose, on “as mutilated” state. Doesn’t win prices, but wins a day…
http://aijaa.com/aqjkCq
HTH, Cheers.
Our new Ovni 395 is currently being made at Alubat for launch in May 2018. Very useful, interesting and pertinent article. Going to have a busy summer refining the commissioning!
Thanks for sharing your thoughts. Looking forward to Part-3.
Hi David,
Glad the timing was good. I have had a rough outline of this piece for a year and was hesitating to go any further with it because I feared it was too specialized, but judging from comments and members sign ups, it seems that it was worth the effort. It’s great to have comments like your to confirm that.
Not all aluminum is created equally.
https://www.proboat.com/2014/11/jade-resurrected/
Hi Chris! Like you I have Yanmar 4JH (whithout any Turbo). It has done 10 000 hours and is fine. Normally this engine will do 22 000 hours. The electric system is not good and made for cars. The starter and its panel is the main problem. I have tried to improve it, but that is difficult. Several oil engineers have given me their solution: They build a stainless steel sink anode box on the hot water pipe line system of the Yanmar. The hot water of the Yanmar is connected to a heating system with floor heating, hot water tapping tank, oil heater for water, electric heating and a 10 000 W truck heater. The sink anode is in this system. The sink must be checked regularly. This is not a perfect solution, but much better than nothing at all.
The perfect solution is of course to have no electricity on the engine and start it by compressed air. I have a Callesen built to expedition standard this way. It has made 130 000 hours and is fine.
To John: Using plywood as isolation material seems a bit original to me: Most ship yards I know use nylon plates. The do not lead electricity and if wet by salt water, they expande a little and their by prevent any leak. Their life time is endless.
Hi Svein,
I don’t really see how adding a “sink anode” to the engine is going to solve Chris’ problem. It’s not going to protect the hull.
And, sure, plastic is a better insulator than wood, but what I wrote was “In theory, damp wood will pass a bit of electricity, but I have never had a problem with this, probably because we paint the ply. If you are worried, you could substitute G10 for the ply.”
G10 is plastic, albeit glass reinforced.
That said, ply is easier to source and work with when building mounting brackets and we check for leakage down to a few thousandths of an amp and see no problems.