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Bottom paint buildup

Discussion in 'Technical Discussion' started by Highlander, Oct 1, 2008.

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  1. Highlander, Oct 1, 2008
    #1
    Highlander

    Highlander New Member

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    Hi guys,

    My boat is a 40' Whisperjet, Yanmar 440's , Hamilton jets.
    The boat has ablative bottom paint. I know this stuff will go for more than one season. As part of the jet service package, the yard rolls on a fresh coat every year. Next season will be our tenth.
    The jets really show an overloaded boat by loosing speed on the top end.
    The difference between full water and fuel compared to 1/2 is about 2 or 3 kts. The queston is --is it worth stripping off the old bottom paint?

    Thanks

    Carl
  2. NYCAP123, Oct 1, 2008
    #2
    NYCAP123

    NYCAP123 Senior Member

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    I'd say it depends on how much you use the boat. 1st, you don't have 10 coats on there as you lose a bunch through the summer as you know, but you also get a lot taken off when they powerwash the bottom in the fall. If you do in fact have a thick coating I'd be less concerned about losing a couple of knots and more concerned with how it is affecting you gph's. Taking it down won't be cheap so balance it against your potential fuel savings, and don't go all the way to the hull for fear of getting into the gelcoat.
  3. Fishtigua, Oct 1, 2008
    #3
    Fishtigua

    Fishtigua Senior Member

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    International Paints do a very good antifoul stripper, worth looking at. 10 years is a lot of paint.

    With waterjets, I would look at pulling them. They have fine tollerances for the impellers so a good service maybe needed.

    Fish
  4. K1W1, Oct 2, 2008
    #4
    K1W1

    K1W1 Senior Member

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    Hi,

    Fish has a very valid point about the wear on impellers and housings although if you are getting a regular Jet Service these guys should if they know what they are doing pick this up if there is wear there.

    A speed difference between 1/2 load fuel and water and full load is not unusual by any means on many boats.

    How much weight have you added to the boat yourselves in 10 yrs?

    Is the hull dry?
  5. Highlander, Oct 2, 2008
    #5
    Highlander

    Highlander New Member

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    Jet service

    Thanks for the feedback.
    Hinckley does the service and they have worked on the jets. One thing that
    added some weight- 2 or 3 years ago we faired and painted the hull. Not much to be done about that now. Every year we strip the boat of all gear and evaluate the need for ever item. Can you imagine we stopped bringing a lobster pot along because it had never been used? This summer we cooked lobster onboard in Machias bay ME. Two at a time in a smaller pot. The ones left in the bucket knew what was coming. The big pot is back on the list.

    The guys at Little Harbor who maintained the boat before Hinckley came had a great attitude. They wanted to make the boat like new every year. I try to keep that going. I test the boats performance every year. 3100 rpm-32 kts
    3000 rpm- 30 kts. those are the original numbers and she falls a little short now. Maybe 1/2 to 1 knot depending on load.

    I don't want much, hah!

    Carl
  6. Loren Schweizer, Oct 2, 2008
    #6
    Loren Schweizer

    Loren Schweizer YF Associate Writer

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    Maybe a Yanmar tune-up is in order? Plus, consider how many hours on those motors...time for a compression check?
  7. Highlander, Oct 2, 2008
    #7
    Highlander

    Highlander New Member

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    Yanmars

    Loren,
    Good point. these engines have 1300 hrs and 19,000. nm on them.
    They have had service on the heat exchangers, oil coolers , intercoolers and trani coolers.
    Does a compression check give you a good idea of overall condition/ life?

    Of course I want them to last forever!

    Carl
  8. Castlerock, Oct 2, 2008
    #8
    Castlerock

    Castlerock Senior Member

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    Have you been getting routine oil sample tests done? That is good indicator if things are starting to wear and service is needed.
  9. Fishtigua, Oct 2, 2008
    #9
    Fishtigua

    Fishtigua Senior Member

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    I'm sorry guys, I hate to say it BUT

    We're all getting old.

    No matter how well we keep everything maintained, wear and tear does come into it. If I was half a knot off my time running the mile at school I would be quite happy today. :D

    Fish
  10. Loren Schweizer, Oct 2, 2008
    #10
    Loren Schweizer

    Loren Schweizer YF Associate Writer

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    Your friendly mechanic should be able to tell you what the numbers are for new, the numbers you now have, and paint a picture of the remaining fuse.
  11. Capt J, Oct 2, 2008
    #11
    Capt J

    Capt J Senior Member

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    It is very critical on Yanmars to have the valves adjusted at the proper intervals (depending on the engine it is either 600hrs or 1000hr intervals). You can lose 5% of your power there. Yanmar also has the injectors taken off and checked/flowed at those intervals as well. Also checking your turbo-charger for wear is in that interval also.

    If you have Ablative paint, and they are only putting 1 coat a year chances are it is not too thick. Is it flaking anywhere? I don't think you are going to gain any speed unless the bottom paint is as thick as a finger nail. I used a product for a customer that goes over the bottom paint and the boat did pick up 2 knots (Sea-Slide) and according to the customer the speed stayed for a full year. I ran the boat before and after.