Material decision made

I completed a second study of material costs and I've decided that my Scarab 650 will be built using plywood instead of foam.  I just can't get myself to pay three times the cost of plywood to build this boat in foam.  I found good prices, but I found even better prices for plywood.   However, prices aside, the decision was made based on a conversation with a fellow boat builder who owns a composite material buisness.  I was speaking with the owner of Express Composites in Minnesota about trying to get a better price on marine foam when he started asking me quesitions about why I wasn't considering plywood.  I thought this odd since he could potentinally loose a pile of foam buiness.  I found out during the conversation that he is a serious wood boat builder, power boats, not sail.  He suggested that prior to applying the wood parts to the strongback, I should coat both sides and all edges with epoxy and allow it to cure.  This seals the wood completely.  I agreed that that would be a great idea.  He also told me that doing so will easily make the plywood last 25 to 30 years.  He then asked if thought I would still be sailing this boat in 30 years.  I did the math and agreed it was highly unlikely.  I then asked him about damage.  I asked "what happens if I hit the dock really hard or run aground on a gravel shore and bust up the fiberglass that will cover the plywood?"  He then told me that the repair to wood would be less work compared to the same repair on a foam boat.  He said with wood, the damage will remain close to the site of impact.  With foam, you can experience delamination sometimes 8 to 10 feet away from the impact site depending on how serious the impact.  It was at that point I decided to go with plywood.

The plans call for 34 sheets of 6mm plywood for the majority of the hull parts.  Not wanting to spend that much money right now, I picked up 25 sheets of 1/4" which should be enough to build the floats and the lower hull.  Here is the pile

The next challenge was coming up with a way to make the scarf joint along the 4' side of the sheet.  I will need to bond 3 sheets together to form a 4' by 24' sheet.  I did quite a bit of internet research and found many different ways to join the panels.  I really like the way Chesapeake Light Craft joins panels in their Kayak kits but the method requires laser cutting or 3 axis routing.  The second best method I found is to angle the end of the sheet with a slope of 7 to 1 based on the thickness.  Some builders use planes, sanders or circular saws.  I decided to use the cicurlar saw method.  I figured if I made sure the blade was square to the fence that is attached to the saw, I would need to tip the saw about 7 degrees to angle I need.  My plan was to clamp the sheet to my workbench with the sheet flush with the end of the work bench.  I would then build a fixture that would attach to the end of the bench that will guild the saw and provide the tilt I need to make the cut.  Here is what I came up with.

Attached to the end of the workbench

I did a test cut on a scrap piece of plywood and fixture works great!  I can't wait to start bonding the plywood.  However before I start that step, I'm going to build the prodder tube assembly.

Until next time...fair winds.

Centerboard is finally complete

While I was back in "material search" mode, I decided to complete the centerboard. 

I left the board shaped and glassed the last time I worked on it.  The only work need was a final sanding and finish.  I was surprised at the amount of sanding needed to get the board smooth  and sleek.  I was also amazed at the number of pin holes uncovered during the sanding.  I sanded the board smooth, applied a fairing compound of thickened epoxy and sanded again.  This is the final result.

I also needed a stainless steel bushing for the pivot bushing.  I ordered some stainless steel tubing with the right I.D and a thick wall so I could include some grooves to help bond it in the board.  I had my machinist friend make the bushing and it turned out nicely.

I finished the centerboard by applying two coats of marine paint.  A funny story here.  I wanted the board to be white so I ordered a quart of bottom paint from Jamestown Distributors in the color called "shark white."  Who would have thought that shark white was actually gray!  I didn't!

More to come....

I'm rethinking foam vs plywood.  Its been a few months since I checked prices so I plan to requote the foam....

Much Progess during early summer 2011

First, some sad news.  I lost my best friend a few weeks back.  His name is Frosty and he was always in the shop with me help any way he could.  Mostly he would lay down and spread the saw dust all round the shop with his tail!  Here is a photo of Frosty sitting on the hose for me.

Rest in peace my dear friend....I will miss you.

As I indicated in my last post, I was starting work on the strongback for the main hull and floats.  I purchased 7 sheets of cabinet grade, 3/4" birch plywood to cut the parts.  The plans did not indicate part layout on the plywood like what is provided for the hull components.  So, I spent the time to draw all the parts using a CAD system and played around with laying the parts out on sheets of plywood that would minimize waste.  I can provide this layout to anyone who requests it.  I also discovered when I was drawing the parts that the longitudinal members that make up the hull strongback were not tall enough.  The way they are drawn on the plan, the bow would extend below the strongback if built per the plans.  I contacted Ray about this and he stated that you just need to block up the strongback for bow clearance.  Not wanting to do this, I just made the parts taller.  To minimize plywood waste, they ended up 600mm high.

When cutting the parts, I cut the slots a little smaller and I fitted each part by filing the slot for a snug fit.  This made the strongback extremely rigid.

The strongback for the floats was built exactly as the plans with no changes.  Again, I filed the slots for a tight fit which is very important for this fixture.  I could easily see the strongback moving if the fit was sloppy which would produce a banana shaped float!  I also drew center lines on both sides of the formers so I could string a line to make sure all formers are in alignment and straight.

The next step is to start building the hull and floats.  I have not had any luck finding foam that is reasonably priced.  From what I found, foam will cost $5500 usd whereas plywood would cost $1800 usd.  I think I am going to build my boat using plywood unless someone can point me to a foam source that is a little more cost competitive.  Next steps, I need to design and build a fixture to cut a scarf joint for joining 1/4" plywood sheets.

Until next time....

Molded Beam - Fail

The first molded beam was a total failure.  The part turned out so, so, but I had to destroy the mold to get the part out.  All the waxing and mold release worked perfectly with the exception of an area on the top of the beam, about the middle for about 20 cm.  This area stuck so bad, the beam still has plywood bonded to it.  Needless to say, I was very disappointed.  However, I didn't get that discouraged to scrub the entire project.  I got out the plans and modeled the beam using a CAD tool and sent the model to a local composite prototype company that often does work for Mercury Marine.  They looked at the design and wanted to meet with me to discuss the project.

When I described all that I had done with my attempt they came up with two suggestions that would have probably gave me success.  First, the suggested that the mold should have been built so it would split or for a side to come off.  Once this suggestion was made, I saw how simple it would have been to make the mold split in half.  The other suggestion was to change the process of laying up the part.  In the instructions, Ray states that you apply a coat of resin to the mold and let it tack up.  Once it is tacked up, you start to apply the cloth as per the laminate schedule and you can not stop until you finish.  The composite company told me that when you lay up a laminate using this method, the part will shrink very tightly to the mold and if the mold is a light weight plywood mold like this mold, it often will suck the mold in when curing making it almost impossible to remove the part.  This is exactly what I experienced.  The composite company suggested that I should have let the first layer of the laminate (chop cloth) fully cure before adding the remaining layers.  This will greatly stiffen the mold and probably prevent the distortion of the plywood mold.

I then talked to them about what it would take to have them make the 4 parts for me.  I instructed them to give me a quote for 4 molded beams, untrimmed and unfinished.  When I got the quote for the mold and four parts, I told them to proceed with the build!  I figured the little extra money was worth knowing the beams will be built correctly and not fail.

Since the beams are under way, I will now focus on building the hull, floats, and finishing the centerboard.  The seven sheets of plywood on the workbench are for building the two strongbacks.

More to come....

Molded Beam Build

Over the weekend I started to mold my first beam.  I grossly underestimated the amount of work it would take to make a beam.  Overall, once the mold is ready to go, it took 10 hours and 2.5 gallons of mixed resin to make one beam.  Here are the details.

On Saturday I spent approximately 5 hours cutting all the fiberglass cloth for the one beam.  When I saw the pile of cut cloth, I was amazed that all that cloth would go in to one beam.  I had everything laid out on the floor so I could easily take each piece when it was needed.  I paid special attention to the unidirectional fabric to make sure I rolled it carefully.  When cut in smaller pieces, it has a tendency to unravel and fall apart.  Roll it once, set it aside and don't touch it until its needed.  After 5 hours, I was itching like I had fleas from the glass fibers, so I called it a day.

The next day, I started by applying a coat of PVA mold release to the already waxed mold.  This release is a water soluble mold release and is recommended to make removing the part from the mold easier.  After the mold release dried for an hour, I applied small pieces of masking tape over the holes in the beam mold for mounting and pivot components.  Pilot holes will be drilled prior to removing the part from the mold.  Next, I applied a coat of epoxy to the mold as recommended on the plans.  Once this set up for a short time, I began the messy part.  There is a lot of cloth in one part and it takes a long time to put it together.  Once you start, you can't quit until its done.  I also recommend using the slowest curing hardener you can find.  I used MAS medium and it was way too fast.  I could feel the resin getting warm before I was finished.  This step took 5 hours to complete.

More to come.....

Work has started again.

I had to take a break from building my Scarab 650 because of a neck injury.  My winter was spent with many visits to Chiropractors, Physical Therapists and Doctors.  Everything is better now so I have started to work once again on my boat.

Quick update on the Centerboard:
The Center board is fully glassed and needs finish work and paint.  I also need to fabricate the pivot bushing and install it.  I will upload photos when complete.

Update on Beams:
The mold has been waxed with 5 coats of mold release wax.  I am waiting for a shipment of epoxy to arrive and then I will attempt to mold my first beam.  I'm very nervous about molding the first part! 

Update on Materials:
Over the winter I've been contacting suppliers of foam to get quotations.  I'm very disappointed at the cost of foam.  I've also priced plywood and I have found the foam is 3 times the cost of plywood.  So, having said that, I'm rethinking my "wood free" boat comment.  I'm working with one, last ditch, supplier in Minneapolis as a source of foam.  I have not received their quotation at the time of this posting.  I'm hoping it will come in better than the rest.  More to come.

That is all for now. 

It has been a while since I've posted anything since I hurt my shoulder/neck/back recently.  I only wish the doctors can figure out what happened and how to fix it.  Meanwhile as I heal, I decided to do some research on materials and design enhancements for my version of the Scarab 650.  For example, as you all know, most boats have some sort of symbol or logo on the mainsail to indicate the type of boat.  The Catalina 22 uses the red diamond with a C 22 in the center.  My Hunter 216 has the blue Hunter logo on the sail.  And, there is a Scarab Trimaran that was built in Canada that has an Egyptian style Scarab beetle on his sail.  I found this really cool design that I'm considering for my sail.  I think it would really be an eye catcher, not that a tri needs to call attention to itself.  Comments, thoughts?

More to come!