Joining the Club - Spindrift 12 plans ordered

[Hirilonde]

...When does the boat stiffen up?  After the bulkhead, frame and transom? Of after the "spot" welds are in place?

Mostly when the seams are epoxied, then more as the bulkhead and gunwhales are installed.

I think you should install the bulkheads, then gunwales and epoxy the seams last of the 3.  That"s what my instructions said, and the order I did them in.  The bulkheads and gunwales give the boat its final shape.  Once the seams are epoxied you are stuck with what ever shape you were in, good bad or otherwise.

[Greg Luckett]

[quote author=Hirilond

[Hirilonde]

That's in the instructions somewhere?? ???

I have a 3 page section titled "Spindrift 9N General Order of Instruction Guide"  Basically it states the bulkheads should be installed during wiring, (nesting and bow in this case, it may be different for non-nesting) and that breasthook, knees and gunwales should be done next.  When these are done the seams are fileted and epoxied.

[cdunc]

The order of construction for the S12 are the same, wire hull (bulkhead, frame and transom as you go), check hull for straightness, "tack" weld your hull, breasthook knees and gunwales, epoxy fillet and fiberglass tape seams inside.

[cdunc]

The instructions call the "tack welds" mini fillets.  Fillets are made with thickened epoxy, so I am assuming that my tack welds should be using thickened epoxy.  Is that a correct assumption?

Update on the video of going 3d.  I cannot find the cable I need to connect the camcorder to the PC.  I will find it or buy a new one and load the video at some point.  I spend 8 hours a day 5 days a week in front of a computer so I would rather spend my off time doing other things, like building a boat.

Thanks in Advance,

Craig

[Ken_Potts]

You are correct - Thickened epoxy for the tack welds.  If you make the tack weld fillets smaller then the final fillets you can fillet right over them to get a more consistent final surface.

And I sympathize about the computer job - Me too.

[Hirilonde]

There have been several discussions about tack welds here.  Many of us don't use them.  The reason is that it is simply unnecessary work.  Once the hull is totally wired, the bulkheads wired and/or temporarily screwed, then the  gunwales, breasthook and quarter knees are permanently installed.  This all assumes you take measures along the way to check for twisting and other misshaping of the hull. 

When you have finished all of these steps it is time to fillet and tape/epoxy the seams.  You can do all of the interior seams in one long step or by sections.  This way you avoid cleaning the blush and sanding of any epoxy.  It also means you get all primary or chemical bonding of the resin used for taping to the fillets.  The wires can be removed after the taping of the inside, again at the end or by sections depending on your work schedule.

[Greg Luckett]

I do not use tack welds and only did it once on the first boat that I built.  I use blocks of wood to keep the wired hull in shape on the dolly.  I do tend to just put a fillet in first, letting it cure, and then later do the interior taping as this holds the hull shape better as I bump into it with my fat belly.  I do the exterior all at the same time: sanding, shaping, filleting, taping.  I may be making a mistake but I do not put the quarter knees on until near the end of the build, and sometimes not at all as I make changes to the transom framing....builder's choice.  Quarter knees are for beefing up a weak transom to side joint for using a motor and are not the only way to accomplish that task.  I do like the looks of them though.

[lbrewer]

I used the tack welds.  I just made them a little smaller than the final fillet was going to be, so that I could fillet right over them and tape the seams while the final fillet was still tacky.  I've done it this way on several different boats and haven't had a problem.    I guess filleting right over the wires and taping the seams all in one session would save a step.  Then you heat each wire individually after it cures to soften the epoxy holding it so you can pull it out.  Each way has been done successfully so I'd use whatever method your most comfortable with.

You can boil a chicken, or bake it, or fry it, or get real fancy and put it on a rotisserie.  Still tastes like chicken!

Larry

[cdunc]

Things have been moving slow on the build.  The weather in Hotlanta wasn't so hot.  It was hard to get motivated to work in a cold garage plus I was worried that the epoxy wouldn't cure.  So out came the measuring tape.  I figured out that the boat will fit in the basement work shop.  I was not building in the shop because I was afraid that if I built in there I might never get it out.  But after some measuring of the window opening and my floor space I decided it could be done.  So now my boat is in a nice warm shop for the winter and all my tools that were spread between the shop and the garage are happily hanging in there appointed spots.  All is good.

Which means I am making some progress.  I have most of the inside seams filleted and taped.  The gunwales have been installed.  I still need to install the knees at the transom. 

When is it okay to remove the temporary center frame?

Craig

[Greg Luckett]

I did not use the temporary frame since the sloop design has the bulkhead further aft than the cat rig design.  I would remove it once the bulkhead is in as you need it out of the way for the seat framing.

[Hirilonde]

I assume you have done the gunwales already?  Because the gunwale is laminated in place it is critical to the final shape and little movement can occur after the epoxy gluing it together cures.  Mine was a nesting version, so it is hard for me to picture what internal structures can be done while the temp is still in.  But the gunwales and knees alone will do a lot to hold the final shape.  Add in filet and taping the interior corners of the hull and it gets really rigid.

[cdunc]

I am getting ready to start building the centerboard trunk.  I read in the Devlin book about using kitchen laminate for the interior of the trunk.  Has anyone used this method?  Any thoughts?  I happen to have some laying around from a previous project.

[cdunc]

On a different post someone pointed out that measuring the resin and hardener by weight is not correct due to the difference in density.  I had been mixing up small batches of epoxy with a 2:1 ratio by weight instead of volume.  Due to the difference I really wasn't getting the 2:1 ratio.  Graham said that the difference in mixing by weight vs volume is too slight to worry about.  In the small quantities I had been mixing up to that point it would be even less significant.  Since I am using Graham's epoxy I figure he would know.

Since I find it much easier to use a digital scale than lines drawn on a plastic cup with a sharpie I decided to improve my formula.  Using 2 small 3 oz cups with equal amounts of water (by weight) I drew lines on the cups.  I then poured the resin into one cup and hardener into the other up to the lines I had drawn.  After measuring the 2 cups I found that the hardener was 30 grams and the resin was 35 grams.  With those numbers I can now measure out the proper 2:1 volume of epoxy very quickly.  I still use the pump for the hardener since it is not as thick as the resin.  So 30 grams of hardener goes into a cup and then I poor 70 grams of resin for an even 100 grams.  If I want to double amount then I pump out 60 grams and 140 grams for an even 200 grams.  Pouring the resin is sooo! much easier than pumping.

This makes mixing up a batch quick and painless.  Just thought I would share this for people to use or to be shot full of holes. ;D

Craig

[Hirilonde]

Yup, that works.  I bet if you did some searching of this site you would find several if not many variations of the same basice idea  ;D

[tom151]

I am getting ready to start building the centerboard trunk.  I read in the Devlin book about using kitchen laminate for the interior of the trunk.  Has anyone used this method?  Any thoughts?  I happen to have some laying around from a previous project.

I've used it for temporary washboards/hatchboards (my boat is kept in salt water). It did begin to break down after a few months. It seemed to me that even the high humidity was a problem.

[Charlie Jones]

Might work fine on a trailered boat.

But what I  do instead is glass and then fill-coat the interior with 3 or 4 coats ( or more) of epoxy mixed with graphite powder, sanded between coats. Makes a pretty slick finish. Just be sure you fill the weave.

I also coat the centerboard itself with the same mix down below where it shows.

[cdunc]

I decided to go with the graphite powder and epoxy instead of the laminate. 

I cut out the sides for the trunk.  The plywood has some twist in it.  Any recommendations on relaxing the twist.  The kingposts will take out some of the twist but not all of it. 

I was looking at my remaining stock and they all have some twist in them from being stored on edge.  I don't really have a place to store them flat.

Thanks,

Craig

[Greg Luckett]

I did mine the way Charlie described.  Try this link to the pictures posted. 

http://www.messing-about.com/forums/index.php?topic=6038.30

[Hirilonde]

The plywood has some twist in it.  Any recommendations on relaxing the twist. 

Try clamping the plywood wracked in the other direction for a few days and see if you can straighten it before you begin.  This sometimes works.

Try matching pieces with the twist in oposite directions.  Clamp the whole assembly to a flat and true surface for glue up.  These will both help, but nothing can guarantee a true result except flat ply and a true clamping surface.  If you are at the end of your ply then I would try it. But a twisted trunk will frustrate you for many years to come.  You really want this to come out straight and true.