F-44SC Catamaran: mast base core

F-44SC Catamaran: mast base core

mast base core

Here's the mast base core.  This chunk will be fully encapsulated with epoxy and multiple layers of glass. I elected to laminate this piece from White Oak.  White Oak is known for it's durability and resistance to water.  ( White Oaks have cellular structures called tyloses. Tyloses give the wood a closed cellular structure, which does not allow water to pass.) further knowledge on White Oak: http://en.wikipedia.org/wiki/Quercus_alba

To further reduce ANY possibility of water intrusion,  all fastener penetrations will first be drilled out oversize with a large paddle bit then the void will be filled with solid epoxy, micro,  aero fill so that any fasteners will have no contact with  the wood.

hull to bridgedeck join detail

Since there are 10 layers of unidirectional glass forming the "flanges" capping each bulkhead, the join areas get 5 layers on the inside and then five layers on the outside.
This outside lamination requires that the foam be removed so that a total of ten layers of glass can form a continuous load path between the bulkhead joins.

cockpit storage

The aft bulkhead now includes a couple of storage spaces. I may eventually install hatch covers here but for now, I think I'll keep them open so I'll have a place to put things that may need to be handy at a moments notice........like maybe a large sawed off mossburg 500 pump action shotgun to discourage modern day pirates......or maybe packs of Marlboro cigarettes to make friends with them......or maybe a copy of "Bennet Carls vest pocket book of jokes for all occasions" to ease any possible conflicts.

What did they do before the days of peel ply?

forward bulkhead

In order to install the cabin top and foredeck, I needed to finish taping the forward bulkhead in place.  Unlike the mast, cabin and aft bulkheads that receive 10 layers of uni on either side, the inner bridge deck portion under the forward bulkhead receives two 8 inch wide lengths of uni directional glass with their ends lapping out onto the forward bulkhead. In this photo, you can also see the "optional" foam strip where the mast support web will be installed.  I chose to use these foam strips along all critical hull to bulkhead joints because they provide a wider base that helps distribute loads more uniformly.

rounding off the corners

The inner corners of the cockpit coaming are formed by shaping foam wedges and bonding them in place. This 8 inch radius corner will be viewed as part of the aft starboard cabin ceiling.

In this instance, I've used polyurethane glue, a few small sheet rock screws and a bit of packing tape to hold the wedges in position while the glue cures. The corners will then be sanded smooth prior to glassing the decks.

stern view

The bridge deck "transom" is now in place. This panel was vac bagged on one side with 24 oz. triaxial glass leaving the exterior foam exposed so that it can be shaped and glassed later when doing the decks. This will allow the exterior aft bridge deck portion to be glassed in one continuous lamination.

bonding the bridgedeck "transom"

Here's an inside look at the bond confirming a good squeeze out of the bonding mixture. Note the temporary screws used to pull the pre molded flanges into the back side of the panel. Obviously if I had skinny 8 ft long double jointed arms I could have taped this panel in place without resorting to all this complexity.

pre molded flanges

Here are the resulting molded flanges to which
i will bond the bridge deck "transom" panel.  Next step will be to scribe the panel, cut and fit it,  swipe a mixture of epoxy thickened with cabosil all over the flanges then bond the piece in place.

closing in the "I" beam

Here's a close up of the aft bulkhead with the two temporary foam pieces that will be used to create internal flanges.  In this case, I've used packing tape over some scrap foam so that I can then form the flanges by laying glass "tape"on the back side of this "packing tape" covered foam.

The Aft Bulkhead

The aft bulkhead get's built up as a major structural member of this ship. It is essentially an "I" beam with the shear web being the bulkhead itself and the flanges being made up of the deck and lower bridge deck sections;  both of which are sheathed with ten layers of uni directional glass. Once this "I" beam is in place, it then gets boxed in from the front by the aft portion of the cockpit and then the aft section of the boat. Since it is not possible to tape the seams of these sections from the inside, tape flanges are being formed to allow these pieces to be bonded onto the lips of flanges.  In the photograph, you can see both top and bottom horizontal foam pieces that are covered with clear packing tape as a release. I'll tape these removable flange pieces in place then once cured, I'll remove the temporary foam pieces to reveal the glass flanges.  Then, I'll rough sand the flanges, trim the bridge deck "transom" piece and bond it in place.....then I'll perform the same dance when installing the aft cockpit piece.

A view from the port side hull

Upper right is a record breaking 3/4 faired gravity bike along with my swing and bubble pop corn popper. 

uni directional glass for hull to cockpit join

It's handy to pre cut all of your glass before you begin any layup. Here are the four sets of 5 layers that will be used on the aft bulkhead joint. Not only does preparing the glass before hand prevent me from getting epoxy all over my scissors, it allows me to be more aware of the resin cure rate.

Aft bulkhead to port side hull join

Here I am preparing to apply uni directional glass along the under side of the aft deck and bulkhead. Since the join area along the under side of the deck incorporates ten layers of Uni glass, in order to insure uniform strength,  five layers are applied along the lower surface then the foam will be removed along the top deck surface so that five additional layers will sandwich the join area.

joining the bridgedeck

Once in place, scribed, trimmed and fitted, I used 1/4 in. lag bolts and squares of 3/4 in plywood to insure a good smooth join line.  After that, I ran strips of duct tape between the blocks then from the top, I filled the gaps with a mixture of epoxy and cabosil. ( the tape keeps the goo in place) After this cures, I can unbolt my blocks and fill the areas under the plywood squares in the same way. 

ladders, boards, straps and chain hoists

Lifting the 24 ft. section of the bridge deck floor single handed with one arm epoxied behind my back.....took some thinking.  I was able to use two chain hoists slung from the rafters fore and aft with a strap running down the length of a ladder while supporting the floppy forward section with a wide board and another strap.