Revised battery area.

Before 

After

 The original battery tray is pictured above.  Located below the quarter berth, it is pretty typical, a piece of plywood with some shallow barriers and two plastic battery boxes retained by nylon straps, brackets, and tiny wood screws.     As built, there was insufficient height for lids for the battery boxes, creating some risk with the exposed terminals. 

 

(Am I the only one that struggles with those straps?   Am I the only one that wonders about the 1/2" wood screws securing 65lb batteries?)

  When I chose to upgrade to LiFePo batteries I decided to revise and refine the battery area to reduce its footprint, create some space improve its security, and better guard the battery terminals.  

I also discovered another repair opportunity - a "floating bulkhead".   See that repair here.

First step was to make a fiberglass tray incorporating a hold-down strap.  To do this I made an appropriate-sized mdf form, slightly larger than the batteries themselves.  The form was covered with waxed paper, and a wet fiberglass layup draped in place to cure.  With this approach, the batteries can sit much lower than before, with a reduced overall footprint.

Multiple layers of cloth and CSM  trimmed on a cutting mat - a handy  tool from another discipline.

That glass was then laid up on waxed paper on a sheet of plate glass, then placed on the form to cure.

And removed from the form.  Lookin’ ugly!  

Trimming.

The aft end shaped to fit the hull curvature 

Stiffeners added to underside.   This part will be epoxied and glassed in place and integrated with the hull and bulkheads in this locker.

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Copper buss bars for parallel connection.  These are equivalent to "0" cable.  ("one ought") 

As I trial fitted the new battery tray, I was also considering the location of the new renogy solar controller, and how the wiring would be routed to it, the house, and start battery.  t  (I had previously run cabling and located a larger group 27 lead acid start battery in the cockpit locker as there was insufficient space for a group 27 and its box under the quarter berth.)

With this smaller platform, it became clear that the start battery would not only fit under the quarter berth, but that it could be positioned to help secure the house bank.  

Furthermore, I realized that the solar controller could also be located in that locker, and that this is also very close to the main battery selector, further consolidating all 12vdc infrastructure.  This significantly reduces the amount of cable involved, and eliminates the need for additional fuses.  Nice!

I now had to make a part to locate and secure the start battery, one that could be integrated into the house bank platform.    After pondering more complex approaches I decided to use the battery itself as a form, and to simply tape dual-layer corrugated cardboard to the battery to provide some clearance.  I covered that with waxed paper as before, and draped a thick dense layup over top.  Done.   

This bracket will be trimmed and fitted into the locker, then tabbed into place .

The start battery bracket fitted, and in the process of being glassed in place.  The screws serve only to secure the piece while the epoxy cures,  these are to be removed and the edges of the parts ground as close to flush as practical prior to tabbing the entire assembly in place.  

 ugly!  ...  tabbing-in halfway done.  I used polyester resin, cloth and CSM for the parts, but epoxy and biaxial stitch mat to fasten the parts in place.   Very strong stuff.

After some trimming and sanding

The roughing in is done, nearing completion with the solar controller installed.

Quarterberth "Floating Bulkhead"

When removing the plywood battery tray to reconfigure for my 2 X lithium Group 31 house bank, I was surprised to notice - for the first time - a poor though fairly inconsequential repair job from Windstar's distant past.

   

As constructed - The  bulkhead in this area was trimmed shy of the hull and the 1" or so gap was covered by fiberglass tabbing that was less than 1/8" thick.  Disappointing really, especially as this is in the area where the aft cradle pad supports the boat when on the hard.   This is not unique to Windstar, and fellow 33-2 owner Bruno L had coined this a "floating bulkhead".  this port-side expanse of hull is not supported structurally, as compared to the starboard side, where the galley bulkhead serves this purpose.  My suspicion is the designer did not intend this bulkhead to float.

The thin web of glass is easily crushed if the cradle pad bears any of the boat's weight.  (as it does)  You can see the hull deflection where the pad rests.   

Repair was complicated by the fact that I do not have locating blocks on the cradle so the yard has some latitude as to where the boat sits.   This season the boat is too far aft, so the pad could not be retracted far enough to clear the hull.  As a result I had to raise and support the stern to allow the hull to return to its natural shape.   The correct positioning will be indicated with blocks for next haul out.   

Plan was:

• Remove crushed broken tabbing, (original and repair) clean and prep area 
• Cut hole for access to back (forward side of bulkhead)
• Laminated oak rib to be sprung and wedged in place
• Fill any gaps with glass-loaded putty
• Create epoxy fillet along length of joint
• Laminate heavy tabbing in place  

Prepping the patient.    You can see the gap between the bulkhead and hull. I cut the damaged glass back to the hull and to the bulkhead edge, ground the surfaces then cleaned with acetone.

 How best to fill the  gap between hull and bulkhead?     I decided go old school and to rip some red oak into strips, coat with epoxy and tape into a beam.  While it was still wet I coated the hull below the bulkhead with epoxy putty then I flexed  the laminations   into place, wedging them  it so that the stack pressed against the hull, bedding itself in the putty, and forming a laminated rib.  

Here are the oak strips ready to laminate 

 

 

Each oak strip was coated with unfilled epoxy, then the strips were assembled into a stack and taped with masking tape at each end to hold the bundle together.  The slippery stack was flexed and slid onto the gap, and further wedged with another few shorter strips,  so then new rib pressed against the hull    Any gaps were filled with the thick glass-filled putty, and smoothed along the edges,  and finally the joint was faired with a big fillet of putty over its length to make a fair radius upon which to laminate the tabbing.

With that still wet, I laid up 5 patches of biaxial stitch mat, (cut in advance), each around  12x9”, double in thickness along The middle, and laid them over the joint, tabbing the bulkhead to the hull.  There is a great deal of overlap, with a minimum of  4 thicknesses of material forming the new tabbing.    Strong stuff! For the heck of it I laid in several lengths of high modus carbon fibre tape I happen to have kicking around (as one does...) 

 Because all the work was done solo, and wet on wet, it was too busy and messy there to stop and photograph each stage, but here's the completed repair, prepped for the battery tray then paint.   

            It ain’t gonna crush now. 

 

Aft Keel Bolt Reinforcement

 

As I worked through sanding and painting the bilges and grinding the limber holes, I decided to give some attention to the aft keelbolt area, which had washers bearing on fibreglass with no extra reinforcement.  No real reason other than I had the area disassembled, had the required materials on hand, was in the process of painting, and it is intuitively a good idea.   

The area in question

A carbon fibre and glass pad was made first, dead flat.   This to be bedded into a dense epoxy/long-strand-glass/cabosil putty, with additional laminations of epoxy/biaxial stitch mat installed in situ.  Photo taken while determining the location of the hole to be bored for the bolt.  

The patient prepped.

The flat carbon/glass pad installed on top of the putty, still  uncured, with the next laminations laid up on a sheet of waxed paper, awaiting installation, wet on wet for the best comformability and bond.    The latter is made of several layers biaxial stitch-mat, each progressively smaller.  This makes a lamination that tapers toward each edge.  This makes sense structurally and finishes nicely.  The thinking is explained further in another blog post.

The lamination inverted and carefully placed, edges smoothed, and waxed paper on top to assist in forming a smooth finish.

And to finish.

While we're at it might as well make a new plate/washer.  Self-explanatory.

And the final result, epoxied and varnished cabin sole, new bilge pump hose, bolts re-bedded and torqued to spec.

Making Fibreglass Parts

 I needed to make some stiffeners for both the keel bolt landings and the updated instrument transducer. Tools are pictured, key are the grooved roller, called I believe a "consolidator", as well as a big sheet of thick plate glass, which in this case, I covered with waxed paper to make cleanup easier. 

I avoid laying up in situ wherever possible as it is much easier to get a dense layup on the bench.

Read up on how to do this, but the key things are to alternate mat and cloth and to use the roller to compress the laminate and maximize the glass content.  You will see the resin float up to the surface.   Let it cure on the waxed paper and the sheet will be dead flat. 

This makes for a very stiff, strong sheet.  In this case I used 6 (I think...) alternating layers each, mat and cloth, and the result was about 3/16" thick.  I think it was 6 oz mat and 9 oz cloth.    I cut the parts out with a fein multimaster, and used an angle grinder to finish the radiused corners.  

If you are laminating onto curved sections of boat, or for whatever reason, need or want to do the layup on the boat, you can use this technique but lift the waxed paper up and apply the wet laminate like a band-aid, using the consolidator to help it conform to the existing structure.   

Tapered parts can be made by planning the work, and using progressively larger pieces of glass.  (or whatever)

ultra-thin flanges for a repair job.

The deck for the mast step.  Around 3/16" thick.

Two thicknesses epoxied together to be used for the second keelbolt.  This is about 3/8" thick, very flat and very dense. 

Hull reinforcement for transducer.  Wood works, but why bother...