centerboards.....

After laminating the foam and center stringer of the centerboard blanks, I am now bonding the high density inserts into position.  The boards require a higher density insert along the leading edge where they contact the forward end of the centerboard case as well as a high density block where the attachment point of the retracting line will be. Once this is bonded in place, I get to become an old school board shaper and have fun shaping them like two big long boards.  I'll have to put on some flip flops, bring out the power planer and have fun shaping per Ian Farrier's Profile specifications.

port centerboard hull slot

Here's the port side hull centerboard slot. This photo was taken looking from stem to stern.  When the cases are bonded and glassed in place, I'll smooth all the edges down and taper the aft portion of the slot to reduce hydrodynamic drag........may even incorporate gap seals similar to those used in the aircraft world. ( I once had a RAY windsurfer with the kick down centerboard fin that had a nice set of flexible gap seals that closed when the board was down....... )

Port case in its place

Port center board case trimmed and fitted.........next step: glassing in place

starboard case in its place

Starboard Centerboard case trimmed and fitted........next step: glassing in place

post cure

Since it's a little cool inside the ship,  I created a post cure "oven" with a little used vac bag and a 750W heater.  Notice the big gaping hole in the port side hull.  that hole will soon be occupied by the port side centerboard case.

port side webs in place

After using a generous amount of a mixture of cabosil, micro balloons and epoxy ( 16 oz of B side, 32 oz of A side, 64 oz of cabosil, 32 oz of micro balloons ) all of the webs are seen here bonded into position.  Once all of the edges of the webs were bedded in with the mixture, two staggered layers of 6 in. glass tape were placed over all of the seams and then smoothed over with peel ply.

foam fillets

Here are the foam fillets that have been numbered to make the bonding procedure a little less confusing.

port side centerboard hull reinforcement

The port side hull reinforcement webs are seen here temporarily placed into position.  The numbers correspond to triangular foam fillet pieces that have been prepared in anticipation of bonding the entire assembly into position.

secret

Don't tell your local composite supplier, but after a successful vac bag process, if you quickly pull the top sheet away from the mastic seam, you can re apply the waxed paper tape and with a little care, you can reuse the bag again and again.  Key to being able to do this is to lay additional layers of "used" bag or sheet plastic on top and bottom of your work so that the epoxy never really comes in contact with the outer bag........saves a little time and a little landfill space.

use of unidirectional glass

ready to roll. ( epoxy that is) ...........the vertical stiffeners that are bonded to the hulls and the outboard sides of the centerboard cases include a modest amount of unidirectional glass along the edges. 

centerboard support webs

Here are the six support webs that will make up the structure that will transfer the loads from the  centerboard cases to the internal sides of the boat.  I have found it easier to first cut and lightly bond the glass over the foam using 3M-77 spray adhesive then simply roll on a good thickness of epoxy over each piece and vac bag them in the usual manner.  After performing hundreds of vac bag proceedures, it's possible to get a feel for how much resin each piecs will absorb.  If you over apply, it won't hurt your part, it will just hurt your wallet.

YIKES!!!!!!!

This photo scares the crap out of me.......I doused the lights in hopes that it would show the laser grid lines that I was using to align the port side centerboard location and now I see some creepy red eyed catamaran monster looking back at me from the port side state room.

Now how many times does a person get to use space age lasers, cardboard, box knives and masking tape all in one day? Here's a confusing shot looking at the port side centerboard case location. ( Ive taken it out again to add all the reinforcement webs)

  The forward portion of each case requires a series of reinforcements that transmit loads generated by the boards back into the hull so Im using a really nice laser level that my brother gave me for christmas to create patterns that I will use to cut the foam core pieces.  

Starboard side centerboard case.

Pre fitting the starboard side centerboard case.  Fot this photograph, I'm standing in the port side forward cabin looking aft.  Takes a bit of trial fitting..... marking interferences, grinding away at them re fitting it, marking more snaggs puling it out again and again.  If you look real closely you can see a 2 inch wide grey strap that I tied into a loop.  I finally figured out that tucking my shoulder under this strap lets me lift the case out by my self without much effort.  Also note temporary stairs leading down from the bridge deck.

It fits.....

This is where the port side centerboard case will live out it's useful life.  I've positioned it in place temporarily and will remove it so that I can install the other support webs.  The case is offset nicely and it leaves plenty of walk way floor space inside the hulls. Notice, however, I have not yet installed the floor supports so you are looking at the curved bilge of the hulls.  Also you will notice that the case fit is not yet complete because the top portion of the case needs to lay flush with the top surface of the side web.   Regardless, I will sleep better tonight knowing that it is going to be possible for me to actually build this cat with centerboards........As Ian Farrier says : It's a lot more work. He's right but I still want to be able to run this ship over unseen sand bars without having to worry about smashing a dagger board or ripping an unwanted slot in a hull. 

Stressful sawing

Cutting a gaping hole in the bottom of the port side hull was a stressful thing to do.  After days and days of stretching string lines, making measurements, swinging plumb bobs, wielding levels, shining lasers and pretty much convincing myself that I knew where to cut my centerboard case hole, I went ahead and cut it......will the case fit...... or will I have to build a new boat?  The wood piece is a representation of the cross section of the centerboard case and here, I am using it to check the fit of the case before I man handle it in place.

Marking the location for the port side centerboard case install

Although this is not the most elegant photograph of the interior of the port side hull, it shows a number of sharpy pen marks that I have made to convince myself that I know what I am doing. ( measure five times, mark three times and cut once )

You can also see the multi layer unidirectional upright web along the left side of the door opening. This, along with several more reinforcing webs will provide ample bonding points to distribute the forces that will be generated by the centerboards.

Port side centerboard case trimming

The forward end of the centerboard case nests into the inner hulls forward of the mast bulkhead.  The lower edges of the case protrude through a slot cut in the boat and will be trimmed to match the curves of the hull.

forward end of port side centerboad case

Here's a close up of the forward end of the centerboard case awaiting an end cap of glass and epoxy.

Port side centerboard case

Here is the port side centerboard case resting on top of the port side master cabin top.  This was as good enough place as any to prepare the edges of the box for external glassing.

reason enough.....

Here are 16 reasons to build a cruising catamaran........nice compared to 9 degrees outside the shop.  Tonight, it's colder here in Hood River, OR than it is in Anchorage Alaska.  The extension cord is running to a small heater inside the bridge deck cabin keeping it a comfortable 75 deg. inside the boat. Maybe I should think about naming her "Thermos"

clamping the centerboard case sides together

With a record cold front on it's way to the Pacific Northwest, what is beginning to become the port side centerboard case is nice and warm inside the main bridge deck cabin. Notice  that the little 750W heater has kicked itself off and it is not having to work too hard to keep things tropical inside.  Outside, the first winters snow is beginning to fall on the metal roof of the shop. 

joining the centerboard cases sides

  To control the precise distance between the centerboard case sides, I've wrapped a 4 x 6 inch wood with tape so that I can use this as an internal spacer.  Next, the plan will be to lay glass and epoxy over the  spacer, add foam along the ends and clamp the centerboard sides in place. Once the epoxy cures. I'll remover the spacer.

Setting up the boards for some hand shaping

Here I am preparing to hand shape one of the centerboards. The Oregon sun was low and strong on this 2nd of December and in honor of such a beautiful day, I decided to set things up outside.

You'll notice the recessed spar which will be covered with 15 layers of 12 inch wide uni glass in between  two layers of 24 oz triaxial glass. Since the final external dimensions will be critical,  it will take a bit of skill to shape these blanks while taking into account the required schedule of glass. Not only will I need to achieve the perfect foil section, I'll need to be able to do that by anticipating the thicknesses of individual layers of glass that will be layed in various places throughout the board.  for example; the leading edge of this board will be covered with additional layers of glass so I'll need to create a recessed leading edge so that it can be built up and fared to the correct external final shape.....it's sort of like trying to work backwards in time.

checking the fit...

OK, since I had to cut the spar out of my blank, shape it, impregnate and glass it with epoxy then bond it back in, Here's the board blank with the spar core pressed into it's home again. Next step will be to bond it back in place using a good thick mixture of micro / cabosil and epoxy.

Tomorrow I'll have a go at these blanks with a power planer and shape them like two big long boards. That will make for a good day.......maybe I'll add a fin box and take one to the Oregon coast for a surf session. or....maybe mount a mast base and windsurf it here in the Columbia Gorge.....or give it to by buddy Cory to do some free style strapless kite boarding with it.......

de bagging the centerboard spars

Here's an interesting way to open a vac. bag.....

Fitting the centerboard spars

Originally, I created my centerboard blanks with the high density cores  (mahogany spars)  all in one. but I decided to laminate, shape then wrap the spar cores individually with glass, then insert them into my centerboard blanks before the final shaping.   Fortunately, I was able to utilize a good portion of my excess foam "cut offs" to create the centerboard blanks by cutting the smaller  foam  pieces into strips and vac bagging them all together.  Notice the board blank on the left is being fitted with the spar.  

a simple post cure oven

so here's a quick post cure oven that I put together to cure my centerboard cores. tomorrow I'll pop them out of the bag and you'll be able to see what this is all about. I placed both spars inside this foam box and used small blocks of styrofoam to close in the edges between two thick foil covered foam sheets. Notice the heater in place as well as the vacuum pump sucking away.

Centerboard spar cores

After laminating, planing, shaping and tapering the centerboard spars, I am preparing to glass them and insert them back into the centerboard blanks.  In this case, I chose to use a light weight mahogany core material as my "high density" spar core.  Once these spars are embedded into the centerboards and laminated with 15 layers of 12 oz unidirectional glass,  these spars will become the primary structural elements in the centerboards.  Here, I am simply pre fitting my glass in preparation of vac bagging the glass onto the cores.  In this case, I used 3M 77 spray adhesive to keep my glass in place then I mixed a whopping amount of epoxy and rolled it on thick.  I then wrapped the spars with peel ply and vac bagged them to insure that I would get good saturation and bond between the wood and glass.  If I do this right, the wood will never know it is part of boat.  ( Being fully encased in glass and epoxy,  hopefully this wood core spar  will never see one molecule of H20 as long as I sail ) 

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.

4 parts in one

 Using my rubber pond liner vac bag table, I'm able to produce multiple parts at the same time while using just a top vac membrane.

vac bagging again....

Time to create a few more parts....here are the cockpit sides and the bow beam support bulkheads being prepped for vac bagging.

bow beam in place

Since I didn't like the idea of having to insert one end in and then cut a hole in the deck of the other hull, I elected to spread both hulls out enough to insert the bow beam in each hole that was cut in the high density insert.  I then brought the hulls back in line.

hoisting the bow beam

chain hoists come in handy when it's just one person.

inspecting the fore stay

Here I am inspecting the fore stay attachment thimbles that support a stainless steel bar all wrapped in place with unidirectional carbon.

carbon

"So who can resist black kittens sitting on rolls of unidirectional carbon?"