5 m Roiwng boat laminte.

Hi All,
I have purchased the plans of a 16' 9 (about 5 m) rowboat from mystic seaport, the plans are of a Whitehall built mid 1870 (porbably) the boat is 16'9 long and 3' 7 wide.
I am going to be building in glass epoxy or composite. I'm committed to epoxy.
The mold has been made in expanded polly styrene ,is very accurate, and is a male mold.
I hope to cover the mold in a release film , and take off a one off hull. I hope to be able to lay up a very clean and fair laminate using mostly cloth ( 200G)per layer, and have very little fairing to do.
if a core is needed then I would laminate this on the inside after release.
I have asked the local suppliers for info, They have seen the Plug/mold so they understand what I'm about. I am waiting to hear from them .
I will probably ask one of the local Surfboard laminaters to help with the glass layup( I think that surfboards are a superb example of craftmanship)
Just Thought you folks would like a stab at this .
looking forward to comments.
Mike

 

Alright, I'm game, I'll opinionate!

First, I'll assume you want to make it as light as practical, otherwise just ignore the following and pile on the the glass 'til the cows come home.

Glass the plug with a couple of layers of 6 oz. cloth or similar (good for practicing), then use putty and primer to fair and fill the weave pattern.

Fit finely scored and perforated foam-core (1/4-3/8?) over the entire plug,(you can add scoring with a ruler and rotary knife with depth stop if neccessary) wax the plug several times, lay up the first skin, wet the back of the core and install it on the wet skin, (hold it together with tape) add peel ply and/or bleeder, breather and a vacuum bag, remove processing materials after cure and maybe do some preliminary fairing, then bag on outside skin. (if you don't have excess topsides to seal the bag against, you can add a flange to the plug before glassing it)

You might want to consider using a slow hardener for this, then post-curing.

Anyway, that's my opinion, so it's obviously the right way to do it.

Happy spooging,
Yokebutt.

 

Hi Yokebutt,
thanks for your comments.
Yip your right I'd like the boat to be as light as possible and while this is not always desireable in a row boat. How ever the displacement is not that large, and I plan to row both 1 and 2 up and I hope to be able to adjust the weight with water balast as and when needed.
I like the idea of laminating directly onto the foam , ends up giving a noice hard male mold to work with, and in the overall scheme and relating to the final costs, is not going to be that costly.
I have had the feeling that a core of some kind was going to be the way to go, thanks for confirming this.
I was going to use peelply then 4 layers of 6 oz ( 200 gram ) cloth, release the "boat" and then on the inside 1 layer 6 oz cloth then the foam and then another 2 layer of 6oz cloth giving a total of 7 layer of 6 oz cloth.
the reasons for doing the foam on the inside is that I think the more glass and foam on the outside the more fairing will need to be done .,, and the surfboard guy will glass the outside ( without the foam ) sothat almost no fairing will be needed, just a flash coat for resin.
I have had the top fairing guy in town look at the plug , and he agrees with the surfboard laminator idea.
so now I'm at
foam core essential , but how much glass?
Mike

 

Mike,
Perhaps the practical way is to make a few square feet of test section on the flattest part of the plug to see how much thickness/stiffness you need? (Stiffness is in cube relationship to thickness)

There is also the possibility of bonding on external stiffeners with lightweight fairing putty while you install coring and inside skin. (like plywood sawn to fit)

The reason I mentioned vacuum bagging is because it really helps to preserve fairness, since it tends to even out the resin content.

How much glass? I would be inclined to start making test sections around 3mm thick, but that is really just a number I pulled out of my ***, answer is that it depends largely on the curvature of the hull.

Thus, in the end, my best advice is to devise a few smaller scale experiments to find out what you need.

P.S. make sure to support the sheer edge well.

Happy spooging,
Yokebutt.

 

Yokebutt,
Havent got to deciding the laminate yet , but one of the locals who seems to know something ,, suggested
that because of shrinckage ,there would be a fair amount of distortion if the outside was laminated cured , released and then the inside and core and glass added.
Maybe I'll end up just using glass carbon and Kevlar ,, I mean its only a 5m rowing dinghy.
Yes I also like the idea pf test laminates and will be starting on the tests this week ( I Hope)
Mike

 

Mike,
I wouldn't be all that concerned about shrinkage if you're using epoxy, it just doesn't pucker up nearly as bad as styrenated resins do. (like poly- or vinylesters) However, if you just make a thin outside skin on the plug and then pull it off, it'll be a helluva floppy piece to deal with, but of course, that's mostly dependent on the amount of curvature in the structure. Composites really prefer swoopy, curvy, and organic shapes. I don't know what you can easily procure down in "soud effrika", but I will still persist in recommending a vacuum pump for doing your laminating, it makes a huge difference in the overall fairness of the layups.

As far as fairing goes, as long as you take an organized and methodical approach to it, it's not that big of a deal. The principle is to go around and use your hands to identify any low spots, then you trowel those spots over-full of fairing-compound, then you use a batten of some sorts to screed the putty fair with the surrounding area, the batten can be anywhere from a couple of feet long to over eight, it all depends on the application, and it can be made from anything spanning from plywood through fiberglass to my favorite, spring-steel. Once you've gotten as far as you can with that, you apply first a coat of primer (with a little bit of pigment added, makes a lovely pastel color) then a second coat of primer with a slightly different color, once cured, you long-board it evenly until you just begin to see the first layer, (don't sand hard on the low spots) now, the unsanded spots are the low spots, so go around again and screed-fill those, sand off the little nubs and ridges you made, then prime and long-board yet again, until you run out of patience. It might take three or four passes to get it right, just don't heap on fairing compound indiscriminately and be stuck sanding for weeks.

As they saying goes back home in Sweden, "If the head is stupid, the body suffers"

I wish you the very best luck with your project,
Yokebutt.

 

Seems kinda daft to buy plans for a heavy, 125-year-old boat, and then build it light. You have the advantage of starting out with a heavy design, that would really benefit from being built to its original weight. Whitehalls and their kin are best when there is some mass behind them, as they can then go through waves without being stopped dead. Stability will also suffer, although you obviously plan on water ballast to alleviate this, which it will do up to a point. Initial stability will be way too high, resulting in an awkward motion, and an inability to get the oars to the water in some conditions.
Forget high-priced laminates like carbon and kevlar, just lay it up with a glass/foam structure, and enjoy!

 

Yokebutt,
thanx for the fairing info , its always worried me , but you make it seem so simple.
The hull and mold , Let me explain a bit,
The boat is 16' 7" or about 5070 mm long and 44" wide.
I draughted the design ( from the lofting figures supplied with the plans ) in Rhino ( a drawing package) faired the lofting, developed sections through the boat at 50 mm centers.
I have a CNC 4 axis hot wire cutter .
I cut the 50 mm slices exact in EPS . I think , to better than .2 mm .
I now have 102 slices with each face exact , and a small flat of 50mm between faces.I have started assembling the sections and will continue this week, so far you can't feel the "joints" where the sections meet.
I'm not gluing the sections together , I'm putting 30 mm 49 gram Glass tape from stem to stern at about 200mm centers. On your sugestion , and it makes sense , I intend to cover the whole hull with 49 gram cloth . this will complete the bonding of the sections .
Now I will make sure that the glass extends above the sheer and I will also paint on a layer of epoxy to seal the cloth against pin holes.
I "hear" you regarding vacuum and will go this route I will investigate equipment this week, I think that and old fridge pump combined with an old gas tank to create a volume of vacuum , would work for the vacuum , but would need to rig up a vacuum breaker for the required vacuum.
Any suggestions on the vacuum pressure that would work?
Keep you posted
Kind regards
Mike

 

Hi Sail design,The original boat was built light ., for a whitehall , but not as light as I intend. It seems to me that the original was built as a one man boat, It had a single sliding seat .
I 'm going this route to try and get a boat that, with the addition of water balast will allow me to row by myself , and without water balast to go 2 up.
I do expect to have to make some sacrfices, but hope that they wont be too bad.
Yes I guess that glass composite is most likely the best way to go
thanks for the reply
Mike

 

Mike,
Vacuum pressure, make a few test-pieces (I know, I know, I keep harping on that) on a waxed flat board and see how it works. You might want to try starting at maybe 5 psi or so, it'll also give you some practice, hell, you might even want to consider bagging up some sheet-stock for your internal structures before laminating the hull.

Vacuum pumps; I suppose a fridge-pump would work, if the capacity seems low, you can always use two, if you think the pump can take it,just rig a T-fitting with a controllable leak and let the pump run continously, you shouldn't need a vacuum-tank, just a resin trap.

One trick I've used for doing big bags with pumps on the small side is to take a flush-mount plastic thru-hull, 3/4" or 1" diameter with a couple of grooves cut in the face, mount it through the bag, top it with a same-size plastic ball-valve and a hose-barb that fit the hose on the shop-vac, open the ball-valve, suck out the bulk of the air, find all the big leaks until it starts getting a couple of psi of traction, then shut the valve and let the small pump take over. (I can sense the idea forming in your head, but almost all shop-vacs depend on the airflow through the hose for cooling, (perhaps excepting the FEIN brand) it can be done, but you have to baby-sit it the entire time so you don't burn the shop down)

Yokebutt.

 

Mike,
A couple more details, put the bag-tape on the perimeter of the bag before you start laminating instead of on the mold, then double it up where you have excess bag, also, double-mask the area of the mold where you're going to seal it, don't get it sticky. Did I mention that it might be a good idea to practice on smaller things first?

Yokebutt.

 

Hi Yokebutt,
I just can't belive that Ive been on this project for over a year.
Thought I'd keep you uptodate on how things are going.
I now have a nice mail mold consisting of 102 sections cut from polystyrene and joined,, I then covered this with a layer of 150 gm glass cloth.
This I have covered with tape 50mm brown , used in South Africa for taping up boxes and parcels.it's very thin and quite strong.
"Someone" once mentioned that a few test samples would be a good idea.
I've done various tests the best todate is 2 layers of 165gm twill weave cloth 2mm core foam vacuumed down and 3 layers of 165mm twill cloth , I've been using Ampreg 22 epoxy resin. thuis is quite ridgid and should be strong enough for a row boat thats not going to be launched through the surf. I will also be putting in a nice Mahogany inwale and various bouancy tanks ( built the same way) and of ciurse seats. all this should help with the rigidity and strength.
I would like all up weight to be in the region of 25kgs
I'm waiting for the local supplier to get some 3mm core foam later this month and will probably settle with that if I can vacuum it down nicely.
kind regards
will keep you posted on progress
Mike