Is all warm water the same?

I received this comment regarding yesterday’s comment on sea strainer clogging:

I have been reading all of the information on the sea strainer blockages. Many folks seem to mention the warm water, which to me, seems suggestive that’s in some way part of the problem. I am trying to understand that because we’ve kept our boat in the Bahamas for 6-9 months at a time for the past 6-7 years. I don’t recall seeing water temps as high as 90 degrees but consistently 87-88 degrees in areas where the water flows freely through the marina. In some of the more secluded marinas where the water does not move so freely I’ll bet the temperature gets even warmer. When we don’t have the boat in the islands it lives in Palm Beach Gardens. I have never seen the kind of growth inside the sea strainers I am seeing discussed. In fact, I just cleaned the engine sea strainers for the first time in 8 years. I did it then more out of guilt than need. The only need to clean the other strainers has been to remove grass. Never do I find any crud or barnacles. So, taking that into consideration, I can’t imagine a degree or two in water temperature makes that much difference in growth. How can it be so bad on the West coast of Florida that one has to put sacrificial metals in the strainers and on the East coast it doesn’t seem nearly as bad? I can’t imagine anything I have is in any way unique.

You’ve raised a very interesting question, that I have no idea about. Our boat was in warm water for months and we never had a problem until Costa Rica.

I really have no idea, although I do have theories:

– The second Nordhavn 68 owner also mentioned that his boat was in warm water for months, with no problem, but that recently when he moved it to a different location he started having problems. It is possible that there are factors besides water temperature; for instance, the depth of the water, and clarity of the water probably makes a difference. I had my worst problems when our boat was in shallow dirty water.

– Once you have a problem, you continue to have a problem. It “grows back”. If you get a serious problem, such as I had in Costa Rica, new hoses may be the only solution.

– Sharp turns in the hoses or thru-hulls exacerbate the problem.

After our run to the Bering Sea, I’m hoping that 99% of future cruising is in warm water, so this is something I really want to get right.

-Ken W

2 Responses

  1. Greetings Jack, and thank you for the compliment.

    I like your idea, although… I’m not sure. The marina at Los Suenos has a non-stop surge which I would think would constantly be freshing the water. That said, it is at the back of a large bay, so perhaps the water isn’t getting freshened. I know that it isn’t the clarity I would have expected.

    And, at Golfito, where we are now, Golfito is almost a completely closed off bay, with horrible pollution problems. We were advised not to go into the water for fear of decease. The entire bay is very shallow adding to the problem.

    I NEVER had this problem on my prior boat, and it was in plenty of warm water. I have a whole list of things I’m going to do to prevent this problem in the future:

    – Thicker hoses (moving from 2″ to 3″)
    – Thicker thru-hulls (moving from 2″ to 3″)
    – Exterior strainer (currently I have none)
    – Straighten the tru-hulls (currently they have a 90 degree turn)
    – Larger strainers on the raw water cooling system
    – Run one of the two thru-hulls at a time (this has been suggested – I’m not positive on this one yet)

    This may all be overkill, but I’d rather be proactive in avoiding the problem.

    Thank you!

  2. Hi Ken:

    I’ve been following your discussion about crud in your intakes. I just returned from a charter vacation in BVI. Upon returning the boat, I had a chance to visit with the charter company’s operations manager, and I asked him how often they had to clean the intakes on their boats. I assumed it would be frequently like you experienced with your boat. He told me that they only clean them out during haul out once a year. I was surprised, and relayed your experience to him. He mentioned that the important thing is that the marina must have water flow. For example, the marina at Nanny Cay has two creeks that run to the ocean, which allow the marina basin to flush itself with tide and current forces. He said that if your boat was sitting in a stagnant marina, that would allow the “crud” to grow more rapidly. I don’t know exactly how the water temps in Tortola compare to Costa Rica, but I bet they are pretty close. My best guess is that your boat is sitting in a stagnant marina. I hope this helps. I would be interested to read thoughts that anyone else might have on the subject. Love your blog. Thanks.

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