Re: [Amel Yacht Owners] Bow locker and hawse pipe deterioration


James Alton
 

Craig,

   Solid fiberglass weighs in around 96 lbs. per square foot versus for instance fir plywood at 36 lbs. per square foot so it is likely that you will add some weight by going with all fibreglass panels to reach the desired stiffness but that would certainly solve the rot concerns permanently.  There are bulking fabrics such as fab matt to build thickness with less weight but I have seen so many failures with those products that I would avoid them myself.  I would think that you could reach the desired stiffness with a total panel thickness that was  thinner than the wood plus fibreglass original so the weight increase should not be as much 3X.  You could add solid fibreglass ribs to the bottom of your panels get the desired stiffness with a lighter weight as compared to a plain panel and I don’t think the ribs would interfere in anyway.  If the panels in my boat rot out at some point, I would certainly consider a similar solution since the anchor locker is going to be a tough place for wood due to the ongoing humidity and dampness.  

    Your idea of using the conduit is interesting as it would never corrode.  I wonder if it would be strong enough by itself and how to secure the ends so that it could never move?  Some kind of a plastic replaceable liner inside of a heavy fibreglass pipe glassed at both ends sounds interesting and permanent.

Best,

James
SV Sueno,  Maramu #220


On Nov 20, 2017, at 4:25 PM, sangaris@... [amelyachtowners] <amelyachtowners@...> wrote:

Thanks, James, for your good input.  


I'm thinking of using Heavy Wall Schedule 80 PVC electrical conduit for the new hawse pipe - easy to work with and should last longer than I. 
May just lay up fiberglass panels for the bottoms.

Craig SN#68


---In amelyachtowners@..., wrote :

Craig,

   Good information.  Just note that plywood panels can definitely rot out if glassed on the top and bottom.  Just think of all of the rotten plywood core decks,  transoms in power boats etc.  If you can however exclude the water from the wood completely or keep the moisture content of the wood below a critical level it will never rot.  Epoxy resin will do a better job of excluding moisture than polyester.  The edge of the plywood panel where the end grain of the wood is needs to be very well sealed since moisture will travel the fastest through the end grain.  Any holes in the panel need to have a ring of epoxy around the hole to prevent any moisture entering the panel, caulking isn’t enough IMO.  A Marine plywood panel should have a waterproof glue but you can buy panels that vary greatly in durability based on the wood species selected.   Wood boats can last a very long time  (one boat that I maintain is 109 years old and the planking is almost all original and solid)  even though they remain wet for most of there lives.  Using durable woods and providing good ventilation are the key points.  For the bow lockers I would suggest selecting a species in the “durable” category such as Fir or Sapele.  Be sure that the panel is solid core with no voids and that the inner plys are of the same species/durability rating.   If the locker contains air that is saturated (near or at 100% humidity due to a lack of venting and water being in the locker) any exposed wood will tend to take on moisture and cannot ever dry.  Opening the locker lids on a nice day or providing some kind of ventilation can help lower the humidity levels in the lockers and thereby extend the life of the original or replacement panels.   

    Thanks for the information about the chain pipe being galvanized,  I did not realize this.  This might be a good place for 316 stainless or perhaps using a very thick fibreglass pipe which will of course wear over time.   

James
SV Sueno,  Maramu #220 

On Nov 20, 2017, at 10:53 AM, sangaris@... [amelyachtowners] <amelyachtowners@...> wrote:


Over the years there have been several posts about the bow locker floors deteriorating due to water rotting out the plywood. I did a minor repair to mine some years ago, but other sections succumbed and I've now removed the entire floors from both lockers. 


Interesting findings:

- Indeed, virtually all the plywood was rotted out, as I expected

-  Surprisingly, the main entry point for water was the hawse pipe. (I thought my deck locker hatches had been leaking, but they had not.) I had seen some rust stains but never found the cause. Turns out the pipe is a standard galvanized one and, over the years, the chain sliding up and down removed the galvanizing and the pipe rusted through. There was a finger width opening on the back side of the pipe at the top and another further d own and these are not at all obvious.

- Having removed the floors I could inspect the bow thruster structure (with some contortions to get myself below the floor level). The structure is made of plywood, well tabbed into the hull and the corners are glassed together, leaving the middle wood surfaces exposed and, surprisingly, unfinished. Oddly, the lower half, from the hull up, is nicely protected by gelcoat. The upper half is not finished at all and the plywood is starting to delaminate on the front side (which is virtually impossible to see with the floors installed). This is where water will run down from the hawse pipe normally.  Fortunately, it is only the surface layers of the plywood that have delaminated and the remainder is still solid, so I can build it back up with fiberglass laminate.

- The floors were only tabbed on the top (getting to the bottom being impractical) and this provides an excellent lip to lay the new floor s on. I'm using marine plywood and applying fiberglass to the bottom before installation to prevent a recurrence.


So, with many of our boats in the 25-30 year range, this area is worth a close inspection. I'm adding a 10" X 16" inspection hatch on the port side locker to allow for future inspections and easier cleanup of the chain locker in the future.


Cheers,  Craig Briggs, SN#68, Ft Pierce, FL








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