1974 Chris Craft aft deck dry rot

Discussion in 'Powerboats' started by jpt1124, Sep 21, 2019.

  1. jpt1124
    Joined: Sep 2019
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    jpt1124 Junior Member

    I'm hoping someone can help or advise me on repairing a section of dry rot on my aft deck (1974 47' Chris Craft Commander). For starters, I'm trying to find out the composition materials of the deck including the type of wood, and what material are underneath it. I will probably hire someone to fix it but want to be somewhat knowledgeable so I am not "taken for a ride" as I have been down that road before. Any help would be greatly appreciated, thanks!
     
  2. bajansailor
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    bajansailor Marine Surveyor

    Good morning JP - have you got any photos of the deck that you could post here? That would be very useful for everybody wanting to help you.
    Do you know the full extent of the rot, or will this only become apparent when you start to rip it all out?
     
  3. jpt1124
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    jpt1124 Junior Member

    Hi Bajan,
    Thank you for responding. I won't know the full extent of the damage until I start pulling that section up. From looking at the surface of the deck (which the previous owner painted) and surrounding cracks, etc., I am guessing probably 1/3 of the deck. Here are two photos. Any help or knowledge on this problem will be greatly appreciated.
    Thanks.
     

    Attached Files:

  4. bajansailor
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    bajansailor Marine Surveyor

    Oh dear, those photos do look rather ominous.
    I found a few sisterships for sale on Yachtworld - the adverts mention that they have fibreglass hulls.
    Is the superstructure on your boat fibreglass as well, or is it timber?
    If it is fibreglass, then the odds are that the main deck is also fibreglass, with a timber overlay.
    If this is the case, then the timber aft deck should be just cosmetic - you could consider ripping it all up, filling and fairing as required, and then simply painting it.
    Are there traditional transverse roof beams overhead (to support the aft deck) in the aft cabin?
    Here is a 1975 Commander for sale - they mention that the aft deck has been renewed, and it appears to be (from the photo of the enclosed aft deck) a type of laminate flooring.
    1975 Chris Craft 47 COMMANDER Power Boat For Sale - www.yachtworld.com https://www.yachtworld.com/boats/1975/chris-craft-47-commander-3024030/
    Here is another, older (1969) Commander for sale - the photo of the aft deck shows a white painted deck with 'planks' similar to yours.
    1969 Chris-Craft 47 Commander Power Boat For Sale - www.yachtworld.com https://www.yachtworld.com/boats/1969/chris-craft-47-commander-3224247/
    If there is not a fibreglass deck underneath the timber (but this would be unlikely if the superstructure is fibreglass), then it would probably be a laid timber deck on a plywood base.
     
  5. jpt1124
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    jpt1124 Junior Member

    Thank you for all the information you have given me, and some pages to view so I can glean some more information! I believe the superstructure is fiberglass. I'm not knowledgeable enough to know about the superstructure or if superstructure and hull are equivalent. I do know that the hull is fiberglass, and the boat has a gel coat finish. I suspect that the superstructure is fiberglass, but I'm still researching that. As for the aft cabin, it is covered by a headliner. I will feel about it in a bit. Here's hoping....
     
  6. bajansailor
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    bajansailor Marine Surveyor

    The superstructures in the Yachtworld adverts do appear to be fibreglass, hence (looking on the bright side) the odds are good that the deck is fibreglass, and the rot shown in the deck planks in your photos is not serious in terms of deck strength / integrity.
    If it is just a small area of aft deck that is rotten, then the easiest thing to do would probably be to simply repair it, by laying new strips of timber in way of the rotten area. If you find various areas (don't be afraid to use a spike on the wood to test it) then it might be worthwhile taking up the whole timber deck. And then either laying a new deck (this would be expensive) or just simply filling, fairing and painting the fibreglass deck underneath.
    Be aware that the fibreglass deck is probably a sandwich construction, with a balsa core between two layers of fibreglass. This might also be rotten - a good indication of this would be the deck flexing noticeably.
    It might also be worthwhile investing in a moisture meter - I have a Tramex Skipper, but they are around US$ 450; here is one that is almost half the cost.
    https://www.amazon.com/Marine-Moisture-Meter-boats-CT-33/dp/B079NLGGG1/ref=sr_1_6
     
    Last edited: Sep 24, 2019
  7. gonzo
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    gonzo Senior Member

    That is typical of a rotten core. The fiberglass skin is relatively thin and can't support the weight without the core. The only proper solution is to cut off the deck and redo it. If you are looking for quick and dirty, it is possible to lay plywood over the deck and fiberglass over it.
     
  8. jpt1124
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    jpt1124 Junior Member

    Luckily, the deck doesn't appear to be spongy anywhere, including, the damaged and surrounding area! I do want to fix it properly before any other damage can occur which may include the core (ugh). I'm guessing 1/3 to 1/4 of the deck needs to be fixed/replaced. I only say that because of the length of the wood. Is there another way to achieve the repair without the deck looking like it was patched? Is fixing only that amount of the deck okay or am I endangering the integrity of the rest of the deck including the core?
     
  9. gonzo
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    gonzo Senior Member

    It is possible to repair just an area. Matching the color and texture is hard but if it was painted before the easiest thing is to repaint the whole deck.
     
  10. bajansailor
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    bajansailor Marine Surveyor

    As per what Gonzo says above - you should do some careful initial exploring by cutting out a section (eg a simple rectangular shape, with boundaries on the 'long' sides in way of the joints in the planks) of deck in way of one of the damaged areas.
    Try to just cut away the timber layer on top, without damaging (too much) the fibreglass underneath.
    You should hopefully then be able to determine what type of wood was used.
    And as the deck was painted, if it is teak then you wouldn't necessarily have to replace the damaged section with new teak - you could use another type of good quality hardwood. of the same section dimensions as the existing strips.
    I wouldn't be surprised though if you find more rot damages, hitherto unseen, when you start exploring and digging out the rotten wood.
    The odds are very good that the core in the fibreglass deck underneath the timber is also in poor condition in many areas, if not all over.
     
  11. Ike
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    Ike Senior Member

    This may be out in left field but, The Arques School of Boatbuilding is in Sausalito. You might want to call them or take a drive over there and talk to one of the instructors. They could probably have a student look at your boat and give you some advice, and they might even be able to do the repair a lot cheaper than hiring a yard to do it. The Arques School | Traditional Wooden Boatbuilding School in Northern California http://www.arqueschl.org/ Usually they build wooden boats but the deck you are dealing with is wood . So they might have some insights. They might want to take it on as one of their projects. In that case you would more than likely only have to pay for materials. But they only use the best materials, so they won't be cheap. Looking at the photos I don't think that's teak. Probably a hard wood of some sort, mahogany or oak.
     
  12. fallguy
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    fallguy Senior Member

    Get a harbor freight oscillating tool for 20 bux and buy some carbide universal tools (somewhere else) and cut away the damage.

    Post pic
     
  13. jpt1124
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    jpt1124 Junior Member

    Just an update. First of all, thank you all for your input, it is of great value to me! I am starting the repair this weekend (removing all the dry rot, damaged core, and prepping it for a proper repair. Once again, thank you! I'll probably post a photo or two of my progress and finished work.
     

  14. bajansailor
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    bajansailor Marine Surveyor

    Excellent! Please do post some photos showing your progress.
     
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