Cold Moulded Boats Illustrated Guide

[Steadman Uhlich]

Originally Posted by UNCIVILIZED

Love her rig. That boomless middle sail really seems to add to her sail area a lot more than would a boomed one. It's very much like those seen on some Wharram designs, such as his Tiki 38'.

On her construction, it's pretty common to have horizontal strips incorporated into a cold molded boat. As it's a quick way to add a lot of wood to her without needing another 3-5 layers of veneers, & concomittantly requiring the insertion & removal of several million more staples. It's also a better way to do things from the perspective of needing a lot less epoxy. Which of course also reduces costs, along with the less layers & staples thing.

I'm certain that we'll never know the true cost of building this boat, but I'm still curious. Ditto on wondering why she has so few berths, & how this works for passage making? Regardless, I want one!

Edit: Jim, I'm sure those hollows aid in keeping I2's decks a bit drier, & her ride a touch smoother


PS: For those interested, there's a lot of discussion, & information on these topics & more at www.boatdesign.net/forums

Good eye!
I almost mentioned the staples earlier. The photos on the blog do show the many staples used in even a small part of the boat. I thought it was good to see that illustrated.

Also, the boomless middle sail caught my eye too.

The top of the blog post also mentions a 70 footer and that this boat was commissioned as a smaller boat.

I also thought it was interesting to see the fabrication of the Carbon Fiber masts (including the boxes of material) and the cast lead keel ballast.
_____________

I have another Cold Moulded boat to feature, showing several photos of its construction. It was done in a different yard (USA) and nicely illustrated too. I will post those photos and links soon.

[Jim Cate]

Originally Posted by Steady Hand

I wrote in an earlier response to DELANCEY that I see no problem with including discussions about other methods that are similar or used in conjunction with Cold Moulding. Strip planked boats are nice and I have admired them too.

As I responded earlier (did you read that?), I had to pick a title for this thread and I picked one that I think will be broad enough to include the wood composite building methods, which can share some methods and materials, but can have differences in technique and some materials use.

As I wrote earlier, I think both can be discussed in this thread. So, you can play or not, that is up to you.

Or if you feel that you want to start a thread only about Strip Planked boats because you think they are too different from a Cold Moulded category and another about Carvel Planked boats, go right ahead.

But, I was hoping you would contribute to this thread in a positive way, because you have a lot of experience sailing on a boat which I think fits within this discussion topic.

That's how I see it.

Steady on, Steady! I guess my attempt at a bit of humor fell flat upon your eyes. But in fact, I think the title is too specific, yet it is your prerogative to call it whatever you wish.

And I'll be happy to add whatever useful bits I can... in fact, I sorta thought that first post hit upon one of the issues involved in modern timber construction: how to get compound and/or short radius curves into a timber hull... something so easy in FRP, not so easy in strip plank, kinda intermediate in cold moulding.

FWIW, Joel White's yard in Maine used the combination technique in most of their timber boats, and there are few yards who can equal their reputation for craftmanship.

Jim

[SailingFan]

Originally Posted by Steady Hand

A Quick Introduction to Cold Moulding a Boat

The following link is the best example I have seen to quickly introduce you to the process of building a CM boat. I encourage you all to view the site via the link to learn or just to see another boat build. Pictures tell the story better than I could.

Nigel Irens 50' schooner
____________

If you are interested in wooden boat building techniques like Cold Moulded (CM) boats and would like to see a recent build, then follow the link to see MANY photos showing the entire build process as this Cold Moulded schooner takes shape. The photos show the CM process very clearly, and also show the casting of the lead keel ballast and the fabrication of the Carbon Fiber masts too. All together, it is a fascinating picture story of how this boat went from concept to design (plans) to finished boat in the water. I enjoyed seeing it and I hope you will too.

This blog post is lengthy but has many photos, good captions, and good descriptions of the entire process. It is one the better descriptive pages I have seen for a boat build, and exemplary for detail and easy viewing as simply scrolling down the long page is a quick way to see the entire process from plans to splash.

Nigel Irens 50' schooner
____________________
Here are some excerpts from that linked site:

Fusion Schooner 50’

Actual march 2015

Design : Nigel Irens

Cruising sailing boat

Hull type : long keel/centerboard

Rigging type : schooner gaff rig

LOA : 14.97 meter

Beam : 4.2 meter

Draft : 1.68 meter ( 3.2meter centerboard down)

Displ. : 21 metric ton

Excerpt:
"As per Lloyd’s regulation hull will be 40mm thickness, in strip-planking/cold molded epoxy, with yellow meranti for the strip and two layer in diagonal of Philippine mahogany wood (red dark Luan) kiln dry, all the hull is completely encapsulated with bi-directional fiberglass, we use local epoxy type PRC#7 who was formulated by the U.S. Navy many years ago when they still had bases in the Philippines."

What I find interesting in this production is that the builder used epoxy for initial sealing, but for some reason (cost perhaps?) switched to fiberglass resin for the outer layer, if I read the website linked correctly. As epoxy sticks to everything pretty well, and vinylester is somewhat less adhesive (and probably a little less water resistant) it seems like making the switch in the process would be less favorable (though cheaper perhaps) than staying with epoxy entirely. Still, epoxy also does not as easily allow water into the material, either. It seems like they should have stayed with the epoxy.

Still, it is an exciting display of construction of the cold molded process, and though I wish they had shown the filleting process for those interested in doing it on a smaller scale, you can see the fillets in place in multiple photos.

I was thinking about doing some stitch and glue boats locally here in Florida, which would have been smaller but of similar construction minus the diagonal lapping, and you would use epoxy only, then glass cloth (preferably biaxial) saturated by a pouring of more epoxy over it on the hull exterior instead of the diagonally applied veneers. I may still do it. Equinox needs a dingy still, and such a vessel would be extremely light and strong for it's size, even as a dingy. I have the epoxy too, so there is that...

Still, all in all, thanks for the thread Steady, because it is very interesting to see how others do things and those of us who are "into" learning about these things can see how the concepts are applied in more massive vessels than we are considering ourselves (or even perhaps to apply them to the larger vessels as well!).

Save

[SailingFan]

Originally Posted by Jim Cate

Steady on, Steady! I guess my attempt at a bit of humor fell flat upon your eyes. But in fact, I think the title is too specific, yet it is your prerogative to call it whatever you wish.

And I'll be happy to add whatever useful bits I can... in fact, I sorta thought that first post hit upon one of the issues involved in modern timber construction: how to get compound and/or short radius curves into a timber hull... something so easy in FRP, not so easy in strip plank, kinda intermediate in cold moulding.

FWIW, Joel White's yard in Maine used the combination technique in most of their timber boats, and there are few yards who can equal their reputation for craftmanship.

Jim

Jim, I agree with you that a wide discussion is a great thing, though it will likely get VERY wide, but that is ok too, it keeps things interesting!

I also am constantly thinking about ways to keep ability to make a fair and smooth hull transitions using stitch and glue techniques, rather than the simple and relatively straight chined hulls that I have seen that used that method. As the boats get bigger, the smooth transition gets easier, but on small boats, you have to either keep getting thinner materials for cores or you have to go thick and sand it all away, it seems!

Keep it going everyone! Let's work out ideas and maybe someday we can make a "group" boat and list the photo of it here at the eventual midpoint of the thread! I am still wanting to get that dingy done, and if I don't get a better living situation together soon, I may have to concentrate on the dingy even more. It is still a relatively blank sheet of paper at the moment (well, more like multiple ideas, and though any of these could work, I have not settled on a single one yet). This thread may give me additional ideas I had not considered yet...

[UNCIVILIZED]

Originally Posted by SailingFan

Jim, I agree with you that a wide discussion is a great thing, though it will likely get VERY wide, but that is ok too, it keeps things interesting!

I also am constantly thinking about ways to keep ability to make a fair and smooth hull transitions using stitch and glue techniques, rather than the simple and relatively straight chined hulls that I have seen that used that method. As the boats get bigger, the smooth transition gets easier, but on small boats, you have to either keep getting thinner materials for cores or you have to go thick and sand it all away, it seems!

Keep it going everyone! Let's work out ideas and maybe someday we can make a "group" boat and list the photo of it here at the eventual midpoint of the thread! I am still wanting to get that dingy done, and if I don't get a better living situation together soon, I may have to concentrate on the dingy even more. It is still a relatively blank sheet of paper at the moment (well, more like multiple ideas, and though any of these could work, I have not settled on a single one yet). This thread may give me additional ideas I had not considered yet...

Since it sounds as if a dinghy is pending, perhaps some references on building would be helpful? I haven't read them (yet), but you might look into the publications by PT Watercraft. Russell Brown is an excellent boatbuilder E-Books

There's also www.westsystem.com & the sister site www.epoxyworks.com where how to's with epoxy, & many, many user projects are show cased.

Plus there's my earlier reference www.boatdesign.net/forums where nigh on everything about boat building, & design, etc. is both welcomed & discussed.

There's also the Wooden Boat Forums.

[Steadman Uhlich]

Originally Posted by Jim Cate

Steady on, Steady! I guess my attempt at a bit of humor fell flat upon your eyes. But in fact, I think the title is too specific, yet it is your prerogative to call it whatever you wish.

And I'll be happy to add whatever useful bits I can... in fact, I sorta thought that first post hit upon one of the issues involved in modern timber construction: how to get compound and/or short radius curves into a timber hull... something so easy in FRP, not so easy in strip plank, kinda intermediate in cold moulding.

FWIW, Joel White's yard in Maine used the combination technique in most of their timber boats, and there are few yards who can equal their reputation for craftmanship.

Jim

Steady as she goes Jim.

Your active positive participation in this thread is solicited, welcomed, requested, anticipated, and will be appreciated!



I also hope you will post some photos of your boat INSATIABLE 2 (I2).

I imagine you have some build photos, or any photos will be interesting to see, especially since you and Ann have enjoyed and cruised your CM boat so extensively.

Please post what photos you can to illustrate a fine example of a CM cruising yacht that goes places comfortably and safely. I think I2 will be an excellent example and will open eyes to how a CM boat could be a great choice.

I know that YOUR example has been a key in my thinking of CM for myself, as you prove its durability and effectiveness in the South Pacific.

[Steadman Uhlich]

Originally Posted by SailingFan

What I find interesting in this production is that the builder used epoxy for initial sealing, but for some reason (cost perhaps?) switched to fiberglass resin for the outer layer, if I read the website linked correctly. As epoxy sticks to everything pretty well, and vinylester is somewhat less adhesive (and probably a little less water resistant) it seems like making the switch in the process would be less favorable (though cheaper perhaps) than staying with epoxy entirely. Still, epoxy also does not as easily allow water into the material, either. It seems like they should have stayed with the epoxy.

Still, it is an exciting display of construction of the cold molded process, and though I wish they had shown the filleting process for those interested in doing it on a smaller scale, you can see the fillets in place in multiple photos.

I was thinking about doing some stitch and glue boats locally here in Florida, which would have been smaller but of similar construction minus the diagonal lapping, and you would use epoxy only, then glass cloth (preferably biaxial) saturated by a pouring of more epoxy over it on the hull exterior instead of the diagonally applied veneers. I may still do it. Equinox needs a dingy still, and such a vessel would be extremely light and strong for it's size, even as a dingy. I have the epoxy too, so there is that...

Still, all in all, thanks for the thread Steady, because it is very interesting to see how others do things and those of us who are "into" learning about these things can see how the concepts are applied in more massive vessels than we are considering ourselves (or even perhaps to apply them to the larger vessels as well!).

Save

I suspect if you write the builder he will answer. Please do that and report your findings here, since you have the question and have raised it.

[Steadman Uhlich]

Originally Posted by UNCIVILIZED

Since it sounds as if a dinghy is pending, perhaps some references on building would be helpful? I haven't read them (yet), but you might look into the publications by PT Watercraft. Russell Brown is an excellent boatbuilder E-Books

There's also www.westsystem.com & the sister site www.epoxyworks.com where how to's with epoxy, & many, many user projects are show cased.

Plus there's my earlier reference www.boatdesign.net/forums where nigh on everything about boat building, & design, etc. is both welcomed & discussed.

There's also the Wooden Boat Forums.

Good post!

I have spent hours and hours at WBF and BD and enjoyed those hours learning about many things. Both are stimulating forums full of experience and ideas. Highly recommended!

And I would love to have a PT11 sailing dinghy! It is my favorite I have seen so far. Sleek, slippery, and sexy dinghy!

The PT11 videos on YouTube are impressive. I was "sold" after watching them, so beware to all, or you may develop New Dinghy Fever!

Here is just one of the several impressive PT11 videos that could cause New Dinghy Fever, so only watch with caution!
Extreme Dinghy Sailing Video
https://youtu.be/lZZ4sIvynWM

[Delancey]

When you laminate veneers in a wood composite boat you are able to orient the grain in the directions that suit your needs as required by the design. 0, 90, 45, 45 whatever. To get started you need some kind of form to hold the shape of the first layer of veneer.

This could be a plug as you might see associated with FRP construction. Alternately, and as is more often and not the case with custom and one-off builds you set up a strongback which incorporates both permanent bulkheads and removable frames and is used as a framework for strip planking the hull form.

This initial layer of strip planking, while often times thicker than subsequent layers of veneer laminations, is typically sized per frame spacing and of the degree of curvature of the hull based on minimum bending radii of the strip planking material. Basically, rather than building a plug and then throwing it away, you are building a plug and incorporating its structure into the finished hull.

Alternately, tortured plywood can be used as a substructure for further veneer laminations. Tortured plywood is a technique for developing compound curved surfaces from plywood that is related to stitch-and-glue construction. Of course strip planking and tortured plywood aren't always covered with further veneer laminations but these tend to be smaller sized boats.

Here is a picture of a tortured plywood boat-

[Steadman Uhlich]

Originally Posted by Delancey

When you laminate veneers in a wood composite boat you are able to orient the grain in the directions that suit your needs as required by the design. 0, 90, 45, 45 whatever. To get started you need some kind of form to hold the shape of the first layer of veneer.

This could be a plug as you might see associated with FRP construction. Alternately, and as is more often and not the case with custom and one-off builds you set up a strongback which incorporates both permanent bulkheads and removable frames and is used as a framework for strip planking the hull form.

This initial layer of strip planking, while often times thicker than subsequent layers of veneer laminations, is typically sized per frame spacing and of the degree of curvature of the hull based on minimum bending radii of the strip planking material. Basically, rather than building a plug and then throwing it away, you are building a plug and incorporating its structure into the finished hull.t

Alternately, tortured plywood can be used as a substructure for further veneer laminations. Tortured plywood is a technique for developing compound curved surfaces from plywood that is related to stitch-and-glue construction. Of course strip planking and tortured plywood aren't always covered with further veneer laminations but these tend to be smaller sized boats.

Here is a picture of a tortured plywood boat-

Good post!

And I like that you mentioned that the strip planked material up above, in a good clear description. Good job.

[boatman61]

Don't know if this is of interest to the Thread.. it used cold moulding techniques combined with a hot glue and vacuum process to make near 100% rot proof decks and hulls.. the idea was to let gravity create an even compression.
The photo is of a Fairey Atalanta.. examples are still going strong today in the UK.. its a no middle way boat.. you either love it or hate it..

Construction methods[edit]
The hot moulding process was an adaptation to post war boat building of the method originally developed by de Havillands in the 1930s for "stressed skin" wooden aircraft production, using layers of thin birch plywood sandwiched together with glue over a male mould and "cooked" in a large oven called an “autoclave” By using true mass-production techniques, Fairey Marine were able to turn out vast numbers of identical boats at an unprecedented quality and price. Moulds were constructed from spruce, built up on a steel base plate. Seven by three inches planks cut to the waterplane sections provided the starting point. Working from the sheerline, the planks were built up in a series of steps, arriving quickly at a close representation of the designed shape. Subsequent fairing yielded finished dimensions. Rebates for the keel, stem and transom completed the mould building process. Although the veneers used to produce Fairey boats may appear to be parallel sided, every one was in fact profiled. Rather than shaping each veneer to fit on the mould, as in traditional boat building, Faireys saved an enormous amount of time by sawing complete sets of veneers to precision patterns. Veneers were produced in stacks of six. Boat were then typically built in batches of 24 or 36. Early boats used 1/8″ spruce ply, surplus to the War Department’s de Havilland Mosquito aircraft programme. When this material became unavailable it was replaced by 2.5*mm agba veneers.
Chosen for its high gum content, agba formed easily without splitting and glued well. All the dinghy classes used just three agba veneers while some of the bigger boats used up to six. Initially all the veneers were laid at 45° while later boats changed to fore and aft outer planking for aesthetic reasons. With the keel, stem and transom in place, veneers were applied starting on the centreline and working out towards the shear. Each veneer was held in place by just three staples at the keel, bilge and shearline. Roller-application of Borden One-Shot waterproof glue preceded each veneer except the first. With all veneers in place a vacuum bag was drawn over the moulding and secured in place using a clamp plate and G-clamps. Early vacuum bags were made from war surplus barrage balloon fabric. After about 1950, individual rubber bags were prepared on the moulds using uncured rubber sheets which were subsequently vulcanised in the autoclaves used for production.[6]
Placed in the autoclave, the vacuum was drawn down to 27/28*inches water-gauge and steam at a pressure of some 50 pounds per square inch introduced. Processing took about 45 minutes at 100*°C. Curing at elevated temperatures under vacuum not only ensured that all the veneers were firmly consolidated – a process requiring many thousands of staples using the conventional cold-moulding process – but allowed for the use of a truly waterproof, single part, high-temperature curing glue. During the curing process the glue impregnated the wood resulting in a virtually rot-proof finished shell. Components such as side-decks were also hot moulded while other parts required for assembly were cut to patterns in the same way as the skin veneers. For one of the more complex boats, the International 14, the time for final construction from bare hull to finished boat was set at 230-man-hours compared to 400–500 hours associated with traditional construction.

[Delancey]

The aforementioned Mosquito Bomber. Mostly hot molded, but I believe also included some tortured plywood components.

[smj]

This is our catamaran. She is of constant camber construction, a form of cold molding.

[Delancey]

Constant Camber totally worth an Honorable Mention. Basically you make a single compound curved mold on which you lay up identical curved parts which are jointed together to make a hull. Here is a picture of a panel coming off the mold.

[Steadman Uhlich]

BOATMAN61,

Thanks for posting the photo and info about the ATALANTA.

It is a boat I have admired and was going to post in another thread I started (Outstanding Boats) and I hope you will copy and paste your same post there too, or I will do that and add some more photos I found. Here is a link to that thread:
http://www.cruisersforum.com/forums/...nd-175264.html

Back to ATALANTA:
It was an extraordinary design and distinctive boat. A real 'eye catcher' and I was impressed when I first learned about them and saw some are still sailing. The styling really looks like it was emphasizing "aerodynamic" design principles that were sometimes seen in motor boats too. Sleek, smooth, and rounded shapes.

And, while it may have been a "Hot Moulded" boat, I do think showing it (and Delancey's good post of the Mosquito) is appropriate in this thread as we can see how the methods of bending wood to make the hull compare.

So, GOOD POST! .