Princess 26

[Howard]

Have begun the process of installing the bottom panels. After struggling with a test of of 4 independent sheets of plywood and keeping them straight and aligned (like herding cats with a broom), I went ahead and joined my bottom panels using butt joints, which were fast to do and which kept the panels dead straight and square. But that did require help to horse them up into place. Once joined together, each panels weighs about 120 pounds.

 

I guess I should have remembered from building the Spindrift, but the edges of the bottom panels do not lie straight to the centerline, but rather open up as a gap in the middle due to the convex outside arc or curvature of the keel planks. In this case, at least a 3/4" gap and maybe more. Too much gap for epoxy to fill. The ends will have to be scribed or marked out in what will appear on the bottom panels (when laying flat on the shop floor) as a gentle, convex arc. (No plan dimensions for the bottom panels.........they are to be simply scribed and fitted into place).

 

If anyone has a fool proof method of either spilling these or scribing them in an accurate manner, I'm all ears. Probably a good skill to learn as I suspect the same thing will have to happen along the edges of the forward planks when I move up there.

 

Good news is that is looking like progress and I'm moving forward again. The way things are shaping up make me think all that fiddling and tweaking of the aft bulkheads was worth the effort.

[wasserboot]

Hello Howard, i have a litte experience with traditional planking and striplanking but not with plywood
But i think it works with plywood too.
I would temporary fasten a long and strong flat batten* on the bulkheads ( i tried to sketch it with photoshop at one of your previous picture)
On these batten i fix with hotmelt glue some thin strips of wood which have a point edge on one side.
This pointed edge goes till the centerline.
Then you lay that batten with the little woodstrips on your bottomboard and mark the pointed edges on your bottom bord.
Then you lay a flexible not too stiff long batten acros the marks and scribe a line along the batten.
That is the edge to be cut.
But i think you do not have to be so exact with the bottom boards.
As i understand the plans (i hope i understand them right), you have to plane the centerline because the deadwood/keel has to fix there.
I hope you understood my worse english

 

*do not twist or distort this batten. Fix it carefully without twisting it.
Trust the given shape of this what looks like a ladder which is cut in the half lengthwise....

[Howard]

Not sure what happened to this post, but in attempting to make an edit, I lost most of it. No matter........

 

In retrospect, my effort to make the two square faced bottom panels fit to the inclined arc that is the bottom keel planks was probably not necessary. Go to post #147 below and you notice that the forward most 33 inches or so of the bottom panels is cut off at the center line. This is done to start the forward diagonal planking.

 

So the 16' long bottom panels was trimmed to about 13 feet. That alone would close much of the natural gap down the center line, and the rest could be taken care of easy enough by trimming from 1/8" to 1/4" off the ends. That could get the bottom panels close enough for epoxy to fill the gap.

 

So if you are following along with intentions of building something similar, I'd suggest you cut out the bottom panels entirely before you worry about the center gap. You might not have much to worry about.

[PeterP]

Howard, WOW that shop! Man you put some effort into it! I just noticed looking at the pictures. Mine is well beyond "bomb hit it" stage. In fact I WISH it looked like bomb had hit it - maybe the sheriff's forensics would clean it up some looking for evidence. Looking good bud! PeterP

[Howard]

Peter:

 

That is not a shop. It's my daughter's horse barn masquerading as a shop. When the boat is gone, not sure what will become of the barn and the bigger power tools that are residing in it. Will probably be left there for my son in law to use. If their kids every decide they want to fool around with horses, the rest can go away pretty fast.

 

Still using mostly hand tools or hand held power tools. Band saw is nice, but my #1 favorite piece of equipment in there is the panel saw. It simply can't be beat for easily and accurately breaking down sheets of plywood and with 40 some sheets used for this boat, it gets used a lot.

 

As for your shop, don't sell yourself short. Shop doesn't build the boat........the builder does. Last time I looked, your Princess looked like heirloom quality furniture.

[wasserboot]

Howard, your string method worked good! 
Well done!
Sönke

[Howard]

Once the panels were ready to mark and cut, another problem surfaced. Plans indicate the diagonals for the forward bottom planks are to start 9 inches aft of BH#2, marked at the chine. Once I aligned the bottom panels to those marks, I discovered the bottom panels were not aligned evenly to the side panels. One side was coming in about 1/4" aft of the other. Off at the chine mark forward and also that much off at the transom. With the two evenly matched bottom panels in place, which I knew were square, and were square to the centerllne, if they were not square to the boat, it meant the boat was not square. You would think being off only that much might not matter. Apparently, it does.

 

You might think that if you have two sides of even length, and they are attached at equal points on both ends, and throughout the middle, they would have to be square to each other. Not so. It turns out one side had more bend in it than the other, which I can only attribute to one of the battens used to stiffen the sides must be stiffer than the other. Meaning one side was flatter than the other. It is possible to have two arcs of equal length, but with different chords, forcing the shape out of symmetry. When setting up the bulkheads and side panels, I had measured diagonals and set the boat up square, but somehow in all the process of working with the keel planks, and bottom panels, it had worked it's way out of square.

 

To fix it, I found a way to jack it back to square, using the marks and side panels as my guide (another good reason you don't want to get too crazy locking this all together with epoxy before all the sides and bottom panels are in place). Once they all trued up, I removed the bottom panels for cutting, and again confirmed square by measuring diagonals from the stem to each outside corner of the transom.

 

In doing so, an interesting thing showed up on the bottom panels. I had scribed them once when they were out of square, and scribed them once again when after being jacked back to square. That 1/4" began showing up all over the place.....on both sides of the transom and on the side panels between BH's #2 and #4.

 

Point being that since the bottom panels do not have dimensions, and are simply scribed and fitted into place, you don't have evenly shaped bottom panels from plans to help you out in seeking a fair and square boat. Plans mention to make sure the transom and boat is square before you attach the bottom panels. That would be good advice to follow.

 

The other thing this demonstrates is that there is an extremely complex interaction of all the various component parts that act together to form the overall shape of the boat. One piece does not have to be off very much to set off a chain reaction of shape changes throughout the boat. Remarkable to me that there are mere mortals capable of understanding how all this fits together and can predict these desired shapes using mathematics.  

[Howard]

On cutting out the bottom panels, once they were scribed along the transom and sides, that was a straight forward process. To rabbit in the land for the first of what will be 1/4" plywood strips that form the forward diagonals, I again used my power planer with fence. Fast, easy and accurate.

 

Last photo shows panels setting loose in their approximate final resting place. Next job will be to true them up and glue them down.

[wasserboot]

You are making good progress!
It seems that you will celebrate the turnover ceremony this years 

[Navegar]

I know you are past this point in your build, but what portion of the centerboard trunk is below the designed waterline?  

I would think at least a minimum of 20 mil of an epoxy paint  film should be applied to  protect all wood surfaces routinely exposed  to water contact.  (a 20 mil film build up is recommended for epoxy  bottom paint intended to prevent osmotic blistering on old (pre-vinyl-ester) fiberglass hulls) .  20 mill requires four coats of most rolled on bottom paint.  if sprayed, it is probably 3 coats.  That will be tuff to achieve if the trunk is first made and then coated.  I would be inclined to build the trunk in two halves, fully epoxy finish the  interior of both halves, and then epoxy bond the two haves together.  

 

how do we get future anti-foulant paint into the centerboard trunk to reduce slime and even barnacle growth inside the trunk?  

[Howard]

As per plans, at it's deepest point the CB trunk dips about 7 inches below the LWL. So it will get an epoxy coating on the interior walls. Not just epoxy, but each side will be glassed with xynole polyester, of which, one layer runs about 1/32" in thickness, and is very abrasion resistant. More so than glass. The CB gets the same treatment.

 

Both will then be painted with epoxy primer.....probably a couple coats, then bottom paint.

 

It should be possible to gain access to the interior of the CB trunk to roll on anti-fouling paint. The top of the trunk is screwed down, not glued down. If memory serves, width of this finished trunk is going to be just under 2 inches.  However, with most CB trunks, fouling is less of an issue inside the trunk than on the bottom so gaining access is not as big a deal as you might think.

 

Also, the CB pivot pin is below the LWL so has to be sealed in place with caps. But those caps can also be removed, so the pin can come out and the board drop out the bottom to gain full access to the interior of the trunk......but only when out of the water.

[Navegar]

As per plans, at it's deepest point the CB trunk dips about 7 inches below the LWL. So it will get an epoxy coating on the interior walls. Not just epoxy, but each side will be glassed with xynole polyester, of which, one layer runs about 1/32" in thickness, and is very abrasion resistant. More so than glass. The CB gets the same treatment.

 

Both will then be painted with epoxy primer.....probably a couple coats, then bottom paint.

 

...

Thanks Howard, I like your plan for finishing the interior of the CB trunk.  

[Howard]

Work put me out of commission for a while, but taking advantage of a short lull to continue working to finish the bottom. Have notched the bulkheads for the forward stringers and have begun the process of fitting in the stringers. Not sure what to make of this as they are not behaving as planned. I can twist them into place easy enough on both ends, but final shape in the middle is not conforming to the bulkheads. They are not twisting as expected in the middle. Part of that may be due to the different nature of the wood of each piece itself, and part may be due to the orientation of the grain. I purposely tried one that is flat grain and one that is vertical grain to see if that made any difference, and apparently it does. The vertical grain piece taking the twist much easier and is more uniform.

 

But in either case, If left as is, you would have to plane about a 15 degree bevel down the entire length of the stringers to get a panel to lay flat on them, plus doing the expected scribing and fitting on the forward end. But even if you do plane a bevel on the outside edge, they won't be laying flat in the notches. They will be hiked up and out the same amount as the bevel you take off of them. It could be I'll need to clamp them down into the notches for each bulkhead and glue them into place there........more or less forcing in intermediate twist all along the way.......not just on the ends.

 

If anyone with experience fitting these in has any advice, I'm open to suggestions.

[Howard]

BTW, plans do not include exact location for the bulkhead notches, suggesting only that they should be "evenly spaced". My first thought for doing that was to divide the distance into thirds (15 inches / 3 = 5 inches. Then center the two stringers on the 5 inch marks. Regrettably, that does not leave them evenly spaced. That leaves them pinched in at the middle.

 

The way I eventually did it was to take the 15 inches, less the space occupied by the two stringers (1.5 inch stringer x 2 = 3 inches), leaving 12 inches......divided by 3 = 4 inches of even gap between the chine and lower stringer,  keel edge and upper stringer and between each stringer. I did it that way for both bulkheads and with them in place, looks reasonable and similar to what is shown on the plans.

[Howard]

Long time.....no update. Work got serious, as did cold weather. Seems we have been below freezing temps more than above it since November. But days are getting longer and the occasional blip into the 50's reminds me warmer weather is coming and I need to be ready when it does. Got started on the CB and CB trunk early on, but moved on. Decided to return to these now. I need to get those ready to go. As soon as the weather warms enough to finish the bottom, I'll need the trunk finished and ready to install.

 

Wes (sorry.....it was Wes, not Joe) was right. With such tight tolerances, the board needs to be finished and glassed, so as to get the king posts and filler pieces right. This can be inside work, so when some spare time presented itself, I took advantage of it.

 

Plans suggest installing the 50# lead tip as a butt joint, bedded in epoxy and the joint reinforced by several layers of glass cloth over the joint. Essentially, the same kind of joint as butting two sheets of plywood together. After horsing that lead tip around, and imagining the type of forces at play on it, either hanging on the end of the board or when the tip is dragging sideways across the bottom, I decided to go a step further and bolt it on, in addition to all the rest.

 

Process was fairly straightforward. I drilled oversized matching holes in the end of the wood CB and lead tip. The stainless bolts are 2 1/2" long and 5/16" in diameter. Oversized holes for the bolts meant alignment wasn't critical. On the lead side, I wasn't sure how well epoxy would adhere to lead, so I hollowed out some lead at the bottom of the holes, so the epoxy plug is larger than the entry hole. No way to pull that out.  I put the head end of the bolt into the wood......threaded end into the lead, backfilled all that with epoxy and set it into place. To help with alignment, I used the PVC pipe clamps front and back. Sliding around on a bed of epoxy, the lead tip slid into perfect side to side alignment.

 

Drilling holes in lead can be done, but there are some considerations. First it is soft enough that it is very easy to drill, but if you are not careful, it will grab your bit, lock it into place and you will play hell getting it out. I started out thinking I would drill small holes, and work my way up. When the holes were small enough to pull a single, intact ribbon of lead up and out, the bit seized up. Once I moved up to a 1/2" size bit, the tip of the bit started chipping off little slugs that the threads pulled out easy. You also need to lube the bits with something. I've heard to use kerosene. But I worried that might leave residue that epoxy wouldn't stick to, So I used water. Dry, drilling stopped. Wet.....it progressed nicely.

 

Anyway, tip is on and board is ready for final fairing before glassing over. Not entirely happy with the results (mainly concerned about how fair the board is), but for an initial effort, this will do. One thing I think we can be certain of, this tip is not coming off.

 

Board now weighs 80 pounds and is a load for one man to horse around. No doubt at all it will drop down. Not sure if it will every come all the way back up. This board, while perhaps not perfect, will allow us to find out.

[Michael Hiester]

Howard,  In the one picture it looks like a small cavity on the lead between the holes.  Did you fill this with epoxy before assembly or is there a small void between the wood and the lead?

[Howard]

The depression you speak of is a "canoe" or dugout shaped void that was created when the lead poured into the mold shrank as it cooled. Common problem when casting metals when you don't allow for it and include a make up reservoir when doing the casting. Live and learn. If I was to cast the tip again, I'd do it different. I will do it different when the time comes to cast the keel.

 

Depression ran about 1/4" deep and was filled entirely with thickened epoxy before setting it in place. No void left between them. Gave that some thought and if a person had routed a groove in the wood part, and backfilled that with epoxy, you might be able to avoid the need for the bolts. That would not be two flat surfaces, with a thin layer of epoxy between them, rather two concave surfaces, with a large epoxy fill between them. A lot more surface area of epoxy to counter all the tension and shear forces acting on the joint. Like dowel pins or biscuits in a wood joint.

[Navegar]

Long time.....no update. Work got serious, as did cold weather. Seems we have been below freezing temps more than above it since November. But days are getting longer and the occasional blip into the 50's reminds me warmer weather is coming and I need to be ready when it does. Got started on the CB and CB trunk early on, but moved on. Decided to return to these now. I need to get those ready to go. As soon as the weather warms enough to finish the bottom, I'll need the trunk finished and ready to install.

 

Joe was right. With such tight tolerances, the board needs to be finished and glassed, so as to get the king posts and filler pieces right. This can be inside work, so when some spare time presented itself, I took advantage of it.

 

Plans suggest installing the 50# lead tip as a butt joint, bedded in epoxy and the joint reinforced by several layers of glass cloth over the joint. Essentially, the same kind of joint as butting two sheets of plywood together. After horsing that lead tip around, and imagining the type of forces at play on it, either hanging on the end of the board or when the tip is dragging sideways across the bottom, I decided to go a step further and bolt it on, in addition to all the rest.

 

Process was fairly straightforward. I drilled oversized matching holes in the end of the wood CB and lead tip. The stainless bolts are 2 1/2" long and 5/16" in diameter. Oversized holes for the bolts meant alignment wasn't critical. On the lead side, I wasn't sure how well epoxy would adhere to lead, so I hollowed out some lead at the bottom of the holes, so the epoxy plug is larger than the entry hole. No way to pull that out.  I put the head end of the bolt into the wood......threaded end into the lead, backfilled all that with epoxy and set it into place. To help with alignment, I used the PVC pipe clamps front and back. Sliding around on a bed of epoxy, the lead tip slid into perfect side to side alignment.

 

Drilling holes in lead can be done, but there are some considerations. First it is soft enough that it is very easy to drill, but if you are not careful, it will grab your bit, lock it into place and you will play hell getting it out. I started out thinking I would drill small holes, and work my way up. When the holes were small enough to pull a single, intact ribbon of lead up and out, the bit seized up. Once I moved up to a 1/2" size bit, the tip of the bit started chipping off little slugs that the threads pulled out easy. You also need to lube the bits with something. I've heard to use kerosene. But I worried that might leave residue that epoxy wouldn't stick to, So I used water. Dry, drilling stopped. Wet.....it progressed nicely.

 

Anyway, tip is on and board is ready for final fairing before glassing over. Not entirely happy with the results (mainly concerned about how fair the board is), but for an initial effort, this will do. One thing I think we can be certain of, this tip is not coming off.

 

Board now weighs 80 pounds and is a load for one man to horse around. No doubt at all it will drop down. Not sure if it will every come all the way back up. This board, while perhaps not perfect, will allow us to find out.

Thanks Howard, you do a great job of sharing and explaining your methods and process.

[Joe Anderson]

When I was adding a lead tip to my centerboard I was thinking about adding some pins for additional strength. Graham said he did not think I needed to and when I thought about it I could see that he was right. Steel pins located in the center of the board can contribute very little to the strength of the board. I do not think the pins will do any harm unless you use less FG in the belief that the pins are contributing to the strength of the joint.

 

The problem is that before the board can flex enough to have the pins start resisting the FG reinforcing on the exterior of the board will have fractured. There is a mismatch between the stiffness of the reinforcement materials and their location in the beam. You can run into the same kind of problem when reinforcing a wooden mast with carbon fiber. The stiffer material will fail first and transfer the entire load to the more flexible material before the flexible material has really even started offering resistance.

 

I am enjoying following your build.

[Joe Anderson]

I suspect I may not have all the details correct as to why the stainless pins contribute little to the strength of the board. It may have more to do with their location in the center, and the strength of the wood surrounding the pins, but regardless best not skimp on the fiberglass.