Composite Boatbuilding 6

Cockpit

Cockpit is where skipper and crews are during the sailing and it’s a part of deck. So to build a cockpit involves building a whole deck.

1. Deck Frame Setting

Before we start setting the frames, we had a little discussion on what it’s going to be like.

We all had a time to think about it and all came up with similar idea; Combination of female and male mold. 

And by the moment, plan for the deck frames didn’t come out and thus, Chris drew the frames plan for the deck.

1.1. Cleaning Up

So the first thing we had to do was to secure the space for the deck frames.

We started to clean up all the mess around space for the deck and to make the floor clean and leveled is quite essential. 

Later, uneven floor brought us quite a trouble and thus, time and extra work. Let me explain it later.

1.2. Grid

Before we draw grid lines for the frames we needed to measure the space to find whether it’s right size for the whole frames setting.

To get the picture of size of whole frames setting, we used long batten as LOA and small stick as a beam.

We couldn’t get the proper space with setting straight and perpendicular to grinding bay so we made it slightly tilted to get the proper work space.

Then, right away, we draw CL and each station using trammel arm. We used very thick marker to draw lines but as you all know, thick marker means high chances of errors. So we drew again using fine marker.

Also we drew lines for wood brace (girder / stick??) where frames will sit on.

When all the lines were drawn, first thing we had to do was fixing the wood brace down to the floor firmly so that we could go on to the next step without any delay.

1.3 Frames

Finally frames came out thorough CNC processing. 

CNC carved out frames from MDF but it still needs to be trimmed with trimmer. Frames have its vee cut for CHINE(is also waterline) and sheer. The reason why it has vee cut for the sheer is that it’s been cut 50cm longer that the sheer for later vacuum use. 

For some frames it doesn’t have full size due to efficient MDF use, so we attached small piece of block to the frames to get the right frames. And also we joined some frames together with gussets.

We didn’t get the Dumpy Level (Theodolite, Auto Level) at the beginning of frame setting, so we used traditional way to set up the frames 1 to 3; 3 metal levels. After that we used dumpy level and story rod.

As we setting up the frames we fixed frames with temporary frames. And problem came up.

When we cleaned up the floor it seems that not all the glue and other things were cleaned up thoroughly and this gave us trouble while we were trying to level the problems. We used 15 degree wedge to level and port side was way too high due to glue and other things we couldn’t get it leveled. Height without wedge on the port was higher than the height of starboard with wedged. Chris gave us solution; Cut out bottom of port side of the frames. While we’re doing this I came up with an idea, rail system for frame setting. Later I will write a posting on this.

So we started buzzing out some frames and here comes another trouble. The one we set on the place of STN.7 was not the right one. So we had to wait for the right frame to come out.

The frame we used for STN.7 was not the exact frame but it has use. On STN7, B/H needs to be attached and it was for that use.

B/H is 8mm thickness and it needs to be on 8mm forward from the STN.7 line and photo above left shows that. 8mm B/H will be placed between those frames. So one frame is real frame and another frame is to hold B/H in position. To fix B/H in exact position and not to be moved while working, we made big circle and placed same diameter of MDF on B/H, so we can fix it with screw while not damaging it.

When all frames were done, we made it secure with braces and diagonal braces.

Next thing we did is to get the measure of cockpit sole.

On every station we got the measures from the CL and with this we could get the size and shape of cockpit sole.

So we got the measures and transferred into the cardboard; lofting.

Cockpit sole was bigger than foam we had so we butt jointed foams to get the right size.

We used 3 pieces of foam to make cockpit sole. First we prepared joint floor with plastic tape on it so glue doesn't stick on it and some wood block to hold foams in position. Then glued and placed with proper weight on it so it doesn't lift up.

After it’s joined firmly, we made it into the shape using the cardboard we drew before.

Then, using sliding bevels and board, we get the bevel degree on each station and beveled it. Later we dry fitted on the frames we found it a bit short sized because we didn’t think about beveling. Actually, I think it’s not a matter of bevel. It’s matter of measure.

We measured width right on top of the frames. But frame has 15mm thickness which means in this case height. And width on 15mm higher than the frame is wider. And we missed this. Anyhow, the gap was not that big and later we could fill the gap glue and sh..

Next we move on to the glassing the bottom sides of the cockpit sole. The reason we didn’t do the both sides is that later we can glass all the deck altogether. And the reason we did glassing on the bottom is damage protection because it will be placed on the frames and people will work on it with pressure – weight.

Since cockpit sole is quite big, we used floor as a lamination board. So we had to clean up the floor.

Laminating stack is as follows. 

Floor or board must be clean and flat so it doesn’t damage the foam.

Release agent can be either was or plastic coating sheet. Perforation film and garden mesh make it easier for the extractor (vacuum machine) to suck out the air inside easily and excess resin move easily.

Before we did glassing, we cut all the cloth we need in proper size and ready.

It is quite important enough space or surplus of vac-bag and be careful on sharp edge because it will damage the bag.

As vacuum is turned on, the dark circle on mesh (excess glue) is getting bigger.

When vacuum is done, we checked the other side of the foam and its face was dotted with glue. Chris told us that if we had perforation film under the foam, this could never happen. So it’s like glue’s stuck under the foam because there was no gap or hole to move through.

Then, we cut the cockpit sole into the size. This was done in grinding bay because foam’s already glassed and we need to use diamond saw. And also cutting byproduct is quite hazardous.

Depth of diamond blade was quite shallow; we had to cut one side and the other side again to cut it thoroughly.

Before we fit the processed cockpit into place, we had to do some processing on frames. Due to the limit of CNC processing, edge between cockpit sole and cockpit side is rounded. It must be sharp angle.

So we grabbed long board and chisel and made it quite sharp angle.

And the cockpit sole we made fitted well on the frames..

Next we made cockpit sides and foams which will be placed between cockpit side and side deck.

To get the curved shape of cockpit side, we used the same methods used in top sides of hull, scribing and scribing tool.  And Chris told us that we need to dram fair lines on the cockpit sole on which cockpit side will be aligned. Without it we can’t get exact point where the bottom edge of cockpit sides will be on. It’s quite important and try to use a batten with same thickness of cockpit side.

Then we butt jointed the cockpit sides and other foams.

Some changes on plan.

When we started, we planned to attach the transom on the hull, but Chris told we should attach the transom on deck side. So this gave us some extra work.

We cut out middle floor brace so that transom can be fitted and moved gusset to the other side of frames. And the foam between cockpit side and side deck needed to be moved in toward B/H so we attached small piece of wood block on the frames.

Since transom needs to be fixed onto the deck, transom also became our job.

Three groups worked together because we had to make Collision B/H, B/H and transom out of one sheet of foam. Somehow we managed to get it and made it butt jointed.

Now we’ve got transom, cockpit sole, cockpit side and foam parts between the cockpit side and side deck. Do we make side deck and glue it altogether or one by one? We made decision that we go for cockpit sole and transom first, then, cockpit side and other thing.

So, first thing to do is for transom, cockpit sole and B/H to be glued together.

We placed transom into the place with clamp and double sided tape. But this double sided tape gave us trouble when we took the deck off the frames. I think if we used the same methods on B/H on STN.7, attaching another frame (sandwiching), it would be much easier. So in this case, if we had long and wide enough board for transom, we could just simply clamp it.

Also don’t forget that all the frames must be taped before gluing as a release agent.

After we attached cockpit sole to the B/H, transom to cockpit sole, Chris gave us a question.

Did you guys peel off the peel ply on the bottom of cockpit sole? And answer was No, which means another work. Peel ply must be peeled off to be glued.

We took the cockpit sole off and cut the peel ply off from where transom will be glued onto.

Then we glued it onto B/H and transom again and we also used masking tape as a holder.

Next is cockpit side. We already got the shape of bottom edge on sole using scribing tool. This time we did bevel on the cockpit side so that it sits on cockpit sole perfectly. Then we get the exact size by dry fitting the cockpit side on the frame and marking from the frame. Thus we got the cockpit side ready. But there was something we still needed to think about.

How are we going to hold the cockpit side in position?

Simply we decided to use the same method we used to hold top sides of the hull. 

But again problem happened. We used those small blocks to hold cockpit side in position and it worked fine. But middle and bottom of the cockpit side was not in fair position and Richard helped us to solve that problem. We made longer bit of those blocks to hold cockpit side fair and quite good.

Then, foam between cockpit side and side deck needed to be glued. Before we glue it, it also needed to be in exact fit by beveling. So I get the bevel angle and tested on the test bit, then made it in fit and ready.

And we used masking tape as a holder. Now it seems that cockpit was all done. But cockpit is connected to deck; we kept working on the deck.

Next thing we did was deck.

First we started from the fore deck. To get the shape and size of the fore deck, we simply attached cardboard on the frame, marked it and cut it out to the shape. We could do another way, spiling (place long strip of wood or foam, mark the distance from a certain point of the stick then transfer it to the cardboard) but we thought cardboard marking is a lot faster. But Chris gave us an idea that we could do it easier, it was kind of scribing, but the thing is I can’t recall it.

As you see photo on left, we cut the card board to and foam to fit right on the blister, but later, when we placed it, Chris made it right next to one of blister foam. And I thought that made sense and we missed it.

Then, we placed cardboard on side deck too and got the shape of side deck. We got the foam and got it butt jointed.

Many butt joints we did before for cockpit sole, cockpit side, and other foam. So it was easy this time and we let Taz and Harrison do the joint.

When glue’s gone hard, we brought it down and placed it on the deck frames to check whether it fits; Dry Fit.

We clamped side deck and size and shape was good enough. Then we started scribing the fair curve of the side deck.

After we cut out the side deck foam to the shape, then, did beveling on the side deck.

When bevel’s done, we went for final dry fit of the side deck and this time we used screw to fix it.

It fitted well. Deck frame and foam itself is 50mm bigger than the actual side deck, so we could use screw to fix the foam to the frame.

So this is what I did before the break and I can guess some other jobs done by other guys on the deck.

Here’s my guess.(They might have done~)

1. Gluing side deck to the deck foam.

Dry fitting using screw was quite good. Then, they glued and fixed it again. When we did screw the side deck to the frame, we pushed foam quite hard toward the cockpit side. So when it’s glued, there might be some forces heading upward (lifting the foam up). To prevent foam from being lifted, they might have some weight on the deck and also taped with masking tape.

2. Blister

Blister foam must be stripped and beveled with proper angle. Blister frame also must be beveled to fit the blister bevel. (Forward part of blister foam also must be beveled or sanded to fit on the deck and to be faded away smoothly). Rounded shape of blister must be marked on the deck so the blister ends (or starts from) there.

3. Glass Laminating.

Glass plate for mast sitting must be placed and another glass plate and carbon cloth has been fitted on B/H to distribute weight (pressure, compression??)

Then they must have cut the glass cloth to overlay min.40mm to max.50mm and lay over it on the deck. Other materials including vac tape, perforation film, mesh, peel ply must have been prepared too. Then, they started laminating glass with ADR246 which is giving more time to apply than usual WEST epoxy resin, peel ply, perforation film, garden mesh and then vac bag. Then, vacuum was turned on. Also at the same time, they might have prepared for splash for later use when we flipped over the deck. Splash was made of really thin piece of foam and coarse glass cloth.

And this is what I could guess when I got back from the break..

Thank you,