Deisel Question

wolverine · June 07, 2022, 02:47:48 PM

The deisel started easy and proceded to remove the sail cover and ties. Once the dock lines were removed we motored down the creek. Checking the exhaust, I noticed black smoke mixed with the water. I slowed down and the smoke stopped. In neutral no black smoke appeared at high (2900) rpm or low. Not knowing deisels we returned to the slip at 2000 rpm with no black smoke.

Can anyone shed some light on what is happening?

CapnK · June 07, 2022, 04:15:05 PM

Black smoke is usually unburnt fuel; ie too rich mixture. Engine maybe not hot enough? Maybe an injector issue? I like to let them warm up for at least 30 minutes before putting them under load.

Black smoke much better than white! Usually white means bad things, like water getting into the cylinders.

Give it a bit longer warm up, and then run a bit longer as well, see if smoke goes away. Fingers crossed, it does. :)

wolverine · June 07, 2022, 07:10:40 PM

The diesel mechanic returned my call and said it's a fouled prop. if it was anything serious, the smoke would be present at low idle too. He said it was fine to use the boat, but if the prop is that fouled I worry about ruining the bearing with an unbalanced prop. So, I practiced backing her into the slip, which was sure to be entertaining to anyone watching. Then I broke the kindle and read for while before taking a nap. I would move her into shallow water and clean the prop myself (she draws 3' with the board up), but the area is teeming with jellyfish. I placed a call with a dive service and I'll have them clean the entire hull. It hasn't been done since last fall.

Frank · June 08, 2022, 08:20:22 PM

Those darn jellyfishâ€¦
Hopefully thatâ€™s all it is and both your bottom and prop will be cleaned up with the diver. Keep us posted

wolverine · June 11, 2022, 03:46:57 PM

Moved the boat into 3 1/2' of water today and went down. Hardly any growth on the bottom, but the prop the shaft were covered in barnacles. I was able clean both, but the zinc that was installed last fall crumbled off. Taking out we motored at 2900 rpm for about mile with no smoke in the exhaust water.

Now I need to replace the zinc. Do they usually only last 1/2 a year or do I have another problem?

Also, how long can I safely use the boat without a zinc? I have a sail to Ocracoke coming up and I don't think I'll be able to replace it before then. Of course the engine is only used to get in and out of the marina, but in the unlikely event the winds blow out, we may have to motor the 40 miles home.

CapnK · June 12, 2022, 09:18:33 AM

The zinc is sacrificial, crumbling due to stray electric current which is attacking it instead of your prop/propshaft/thru-hulls. Not sure what shape it was in when you bought the boat, but if new and it has been wiped out in just 6 months that is a short time period. I would err on the side of caution and replace as soon as possible. If you have room on the shaft for 2 of them, add another, it won't hurt and only help.
The current could be coming from faulty dock wiring, or a boat with a grounding issue, yours or another nearby. As long as a zinc is there it wards off the bad effects taking a toll on other, more expensive and harder to replace parts of the boat. Hope that helps!

wolverine · June 12, 2022, 09:37:16 AM

Thanks Capt. The zinc was replaced last September and crumbled when I touched it. There isn't electricity at the docks yet. There is a pontoon boat with an outboard 2 slips to starboard and another sailboat that looks abandon 6 slips to port. Sounds like the problem is with our boat.

CapnK · June 12, 2022, 11:22:33 AM

If you don't have time/etc to have a shaft zinc installed, you could use a "fish zinc":

https://www.defender.com/product.jsp?id=150598

wolverine · June 12, 2022, 01:23:39 PM

I didn't know there was such a thing. I can see having one aboard at all times for situations like mine.
Thanks!

wolverine · June 15, 2022, 10:32:56 PM

Talking with my neighbor, he had a regulator he lent me, as mine is in storage up north along with most of my dive equipment. Luckily my full tank was accidently loaded into the truck when we moved here. I moved the boat into 3 1/2' of water and sat on the muddy bottom replacing the zinc. I intended to install 2 zincs, but I didn't start until late afternoon, and once the sun was behind the trees the murky water was impossible to see through. Now all that is left is to top off the fuel tank and pump out the head. Then the boat will be ready for grandson and I to sail to Ocracoke.

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Deisel Question