Engine Bed Inserts for twin SD20 Yanmar Sail Drive units

This photo is a bit out of order but while I'm finishing up the centerboards, I wanted to get going on the engine mounts.  These parts were cut from 1/2 in. 6061-T6 Aluminum plate.

These beautiful parts were water jet cut by the guys at Versatile Supply in Bingen Washington.  http://www.vsisurplus.com/ ( see active link on the list at right)   They have a brand new "state of the art" water-jet cutter that generates 87,000,000 PSI ! The machine  introduces small rubies into the stream while it controls X &Y to within a thousands of an inch and it has a curf thickness of about a human hair.  This amazing machine will cut through 8 in. plate steel.  They are a family business and I would recommend them to my mama.

Monday I will deliver the parts to Schooner Creek Boat Works   http://www.schoonercreek.com/  ( see active link on the list at right) where they will serve as inserts that will be placed in engine bed molds to produce two SD20 Yanmar Sail Drive Units engine beds.

The boss

"Tang", waiting for me to finish his boat.

The big picture

I had a request to add a "macro" photo of the cat and as you can see, I've got a complex system of order going.  Since I only have a few feet on either side of the ship, I end up using the central portion under the bridg deck as my primary shop area.  As you can see, I keep the shop spotllessy clean and orderly just like the assembly area of a NASA space craft. 

Along with a few bikes, kites, sea kayaks, electric cars, a metal casting furnace and a hundred thousand hand tools, see if you can find the watchful eye of "Tang"........he's perched on the seagull striker; which in this case we'll call a Macaw striker.

port side centerboard blank ready for glass

Fitting High density inserts into the centerboard blanks

Here's a work in progress shot of adding the high density reinforcment areas.  As you can see, I used a little florescent paint to mark the sections of foam that needed to be removed so that the High density blocks could be bonded into place.  The high density foam is a 12 lb per cubic ft density where the other foam is a 4 lb / ft^3 density like the rest of the boat.  The square block in the foreground will eventually contain a tube that will allow the retract line to terminate inside the board with a knot.

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.