Monday, August 29, 2011

Foot Bensons

Over the weekend I also constructed and glued down the foot bensons.  Of course, the primary purpose of the bensons are to keep the crew from sliding to the other side in a strong wind, however it turns out that they are perfectly placed to get rid of a little bit of flex in the cockpit floor.  I'd like to think that I planned it that way, but . . .

 The picture to the left and below show the results so far.  Like most everything else in the boat, these were made out of 1/4" hydrotek.  I cut 3" strips for the outside pieces and 2 3/4" strips for the inside and glued them at a 90 degree angle.
The only tricky parts were cutting the end angles and the end caps.  I cut the angles and the end pieces before committing anything to epoxy.  In retrospect, it would have been easier to just glue the side pieces together and then cut the end angles on the table saw after they were done.  In any case, the bensons came out very nice.  Finally, I rounded the edges and set them in place with thickened epoxy. I will filet the edges of the bensons prior to glassing the cockpit.

Sunday, August 28, 2011

Bow Prod

The bow prod looks good and it was time to create the receiver sleeve for the prod.  As before, I created the receiver tube out of carbon fiber sleeves from Solar Composites.  This time however I made to significant changes in the fabrication, 1) I did not vacuum bag the item, and 2) I put the Kevlar composite sleeve on the inside rather than the outside.  Other than the look, the primary benefit of using carbon/kevlar is that the kevlar is much more resistant to long term wear and abrasion than carbon fiber.  

Of course we want the receiver tube to have a slightly larger inside diameter than the outside diameter of the prod.  So I used the prod as the mold for the receiver, and wrapped 6 mil plastic around it several times in order to insure that the receiver tube would have the necessary clearance from the prod.

As I mentioned above, I did not vacuum bag this part.  Instead I just hung the prod from the ceiling of the garage, put on the four layers of sleeving material in the same way that I created the prod previously, painting each layer with epoxy.  The layers were taped to the mold (at the top) and then I simply stretched each layer by pulling downward.  Finally, I wrapped the whole thing in release cloth.   The picture on the right shows the sleeve hanging with the release cloth still attached.
Once the epoxy hardened, I removed the release cloth and pulled the finished receiver tube off of the prod and then cut it to length on the table saw.

The picture to the left shows the fitting of the receiver tube through the starboard side of the bow.  The picture below show the tube tacked in with a bit of thickened epoxy.
The next step is to reinforce this area with some 12 oz carbon fiber cloth.  I need to add some reinforcing to frame 18 as well to hold the back end of the receiver tube more securely.

Wednesday, August 24, 2011

Bow Prod

So I got it in my head that I could fabricate my own bow prod out of carbon fiber sleeves.   As described below, I previously built a carbon fiber tube to use as the well for a crane to lift up the keel.  This was quite a bit larger undertaking.  The "mold" for the prod was a section of 2" PVC pipe from Home Depot.  This pipe has an outside dimension of 2 3/8".  I sprayed the length of tube with plain old Lemon Pledge furniture polishing wax.  and then wrapped the pipe with polyethylene sheet prior to pulling on the carbon fiber sleeve.  I didn't have the courage to try this without the plastic sheet, but I think that it would be possible to just mold the tube over the PVC pipe directly.  Lemon Pledge actually works pretty well as a release agent.  Some time in the future I might experiment a bit with this.  

Pulling on the first layer of CF sleeve is pretty easy.    This stuff works just like the finger traps that you buy in Chinatown however and will bind if you pull too hard on it - you almost have to push it on.  I then just painted the entire length of the sleeve with epoxy. 

 For subsequent layers, it is best if you roll up the ends axially (like you would a sock) and then push them together to form a very wide pipe.  It is pretty easy to slide this wider "pipe" over the previous layers, and then expand it outward from the middle.  For each layer, I then painted on the epoxy.  

I used three layers of heavy 3" carbon fiber sleeves and (more for aesthetics than anything else) an outside layer of a Kevlar Carbon fiber weave.  I then vacuum bagged the whole thing.  

I hadn't done a vacuum bag on something this large.  It came out pretty well.  The surface under the top of the bag is absolutely beautiful.  The bottom collected some excess epoxy which I had to remove with a Stanley Sureform and some sand paper.  If I had it to do over again, I think that I definitely would have used release cloth between the bag and the tube.  
In any case the tube came out pretty well.  The whole thing weighs less than four pounds  and it is incredibly rigid.  The tube is very round except for the last few inches near the ends.  I'll just trim both ends.  This will leave the tube a bit short, but I'm going to put a tapered tip on the outside end anyway, so I'll just make this tip a couple inches longer than I was going to.

If I had it to do over again I would not have used the Kevlar composite on the outside layer.  Carbon fiber sands very easily whereas Kevlar does not.  Also, Kevlar is less UV resistant.  I don't view that as a big deal however since the pole will be retracted most of the time.  Finally, in retrospect, I think that I could have gotten a very nice tube without the bagging by bunching the four sleeves together at one end and then tying a string to them, hanging the whole thing from the ceiling, then tying a weight to the other end, and then wrapping the whole thing in release fabric.  I say this because the tube looked really nice before I even put it in the bag.  

Next up is to fabricate the receiver tube.  Of course I'm going to use the prod as the mold for the receiver.  I don't think that I'll vacuum bag the receiver.

Finally, I don't have an exact cost on the tube since I bought more sleeve material than I needed.  But roughly the prod and receiver are going to end up costing me about  $300.  This would have been a bit less if I had just used carbon fiber.

Tuesday, August 23, 2011

Forward Deck Glued Down

 I decided to go ahead and glue down the forward deck rather than wait for the completion of a few things that I have to do in the cabin of the boat.  Most notable is fabricating installing the bow prod.  I'm still debating the merits of having an internal assembly for this, or to put it on top of the deck.  I've more or less decided against having an articulating prod (ability to move side to side).  So I decided to commit the deck to epoxy, and then crawl around inside if necessary.
 You may see in some of the pictures, small holes along the edges of the deck.  In addition to using weights to hold down the deck while the epoxy cured, I used 1 1/4 screws to make sure that I got a good seal along the gunwales.  The screws were removed after the glue set. 

Sunday, August 21, 2011

Cockpit floor and sides are in.

 I cut the cockpit floor for the boat quite a while ago but it turned out that I did not make it wide enough at the front end of the cockpit.   Also with all of the other work going on in the center and aft end of the boat, I did not glue down the floor.  I removed the floor and scarfed on a couple of side pieces and re-cut the floor to match the cockpit side pieces.  Once that was done, I "flow coated" the bottom of the floor,  then mixed up a whole bunch of epoxy goop using West system 403 filler, coated the tops of all of the support members and then glued the whole thing down. 
Of course it's important to get good contact between the floor and the underlying supports while the glue dries, so I used weights and some of the lead ingots that I bought for the keel bulb to hold everything down.  

After the floor set up a bit, I then filleted the cockpit sides and floor joints.    My plan is to reinforce the outside of these joints (inside the boat) with glass biax tape.

Keel Crane Well

 We are planning on sailing this boat in lakes where we need to get in and out of fairly shallow water.  Because of this, I've wanted to have an arrangement where I can easily retract the keel while still sailing.  I decided to build a keel crane but need a place to secure the crane while it's in use.  So borrowing a bit from a Melges 24, I decided to create a well just aft of the keel.  So i could have made the well out of almost any material including wood, but since I'm planning on constructing my own bow prod and sprit out of carbon fiber sleeves, this presented an opportunity to practice vacuum bagging a tube.   I bought carbon fiber sleeve material from Solar Composites and went at it.  I was extremely pleased with the result.  Three layers of heavy carbon fiber sleeves resulted in an extremely stiff tube. 

 Next up, I needed to construct a platform to hold the well-tube. I built a platform out of three pieces of 3/4" hydrotek (left over from previous laminations).  One was used as a base, the other as the top of the platform, and with the third I cut a hole slightly larger than the OD of the well tube.  The platform is supported by two pieces of 1/4" plywood, and the whole thing is reinforced with 12 oz. carbon fiber cloth.
The picture to the right shows the completed well.  The carbon fiber tube will be trimmed to the height of the deck after the cockpit floor is glued on.

Wednesday, August 17, 2011

Chainplates are in

 I'm getting to the point where I want to glue down the deck and I wanted to install the chainplates before that event.  A few builders installed the chain plates after their decks were installed.  Needless to say they were working in very cramped quarters trying to get those things in.  In any case, I looked around trying to buy chain plates and finally I asked where people get these things.  Jon from Critical Twist sent me drawings done by Kevin from Pipe Dream.  When I saw the drawings I figured that I could build these things myself.  Of course this kind of thing would be pretty easy to build with a nice milling machine, but my drill press with a crummy cross vice would have to do.  To start off I ordered some 316 stainless.  I thought that I pressed the button for 1/8th inch mirror finished plate, but I received 3/16th in mill finished (dark).  In any case after cutting the metal to size with a Porter Cable Tiger Saw (I tried a cutting disk, but a couple of those broke apart) I used the cross vice to get the holes aligned and spaced evenly.  I then built the backing plates using the same methods.  The backing plates were smaller than the ones in Kevin's drawings in order to save a bit of weight.  I figured with the thicker material that this would be OK.  Finally, it took a whole lot of work to clean up the 316 to a nice shiny finish.

 As everyone recommends in their blogs, I over-drilled the size of the holes in the chain plate gussets, filled them with epoxy/filler mix and then re-drilled the holes to the appropriate size.  The picture to the right shows one of the chainplates installed on the gusset.  
 The picture to the left shows the backing plate.  As you can see, this is quite a bit smaller than the chainplate itself.  
Finally, the picture on the right shows the chainplate protruding through the deck.  The slot that I built on this side of the boat was perfect.  The one on the other side was not so great, however I'll fill the gap in when I glass the deck.

Next up, I'm going to remove the chainplates, finish fitting the deck together and glue everything down.  I'm still thinking about how to add flotation to the boat.  I'm thinking about adding foam under the entire length of the deck.  I might do this with normal pink foam from Home Depot, or use expanded polyurethane foam.  

Sunday, August 7, 2011

New sticks for the i550

 I took a week off of building the i550 for vacation in Maine.  We took along our e-scow.    For those who haven't sailed one of these they are a real hoot, however in a good blow they are a handful (and more) and you really need some beef on board, just to hold it down.  They also, have dual bilge-boards (you retract the one not in use), running back-stays, and a whole lot of strings to pull.  In fact when we decided to build the i550, I was looking for a high performance boat that two of us could sail alone.  It is definitely simpler - we'll see if it is easier. . .

On the way back from Maine we took the opportunity to stop by at Dwyer Mast to pick up a couple of sticks for the boat.  The e-scow worked out pretty well as a shipping vehicle.  We just duct taped the new spar to the mast from the scow.  We bought a 29' 6" DM4 mast and decided to go with the DM5 section for the boom.  Jay at Dwyer suggested keel stepping the mast, so we won't cut the spar until I make the decision on cabin top vs. keel mounting.  I also did not buy any accompanying hardware yet because I'm still deciding how to rig this thing.  I'm thinking about creating the spreaders out of carbon fiber.