Designers Working Specifically in Strip Plank

[potomac]

I think that strip plank really offers a lot of benefits for solo builders of small, medium sized sailing craft (30'-34' range) . I am personally quite enamored of the Alden Malabar Jr. and Malabar Sr. designs and have thought of trying to convert them to strip plank, but also think that there is probably a real benefit to working with a living designer, designing specifically for the method I am contemplating. Can anyone suggest designers who design specifically for strip plank?

I know Ted Brewer does some strip plank designs and I believe the NIS boats can be done strip plank, but I think the sharpie hull form while perfect for my home waters would be limited in terms of cabin size and cruising out to the eastern caribbean.

[Sayla]

I think that strip plank really offers a lot of benefits for solo builders of small, medium sized sailing craft (30'-34' range) . I am personally quite enamored of the Alden Malabar Jr. and Malabar Sr. designs and have thought of trying to convert them to strip plank, but also think that there is probably a real benefit to working with a living designer, designing specifically for the method I am contemplating. Can anyone suggest designers who design specifically for strip plank?

I know Ted Brewer does some strip plank designs and I believe the NIS boats can be done strip plank, but I think the sharpie hull form while perfect for my home waters would be limited in terms of cabin size and cruising out to the eastern caribbean.

Do you mean strip plank without cold mold or sheathing, or standard strip plank based composites?

If the latter, then

Ed Burnett
Mark Smaalders
Paul Gartside

And check out this build of a classic:

http://www.franklinboatyards.co.nz/s...phans-progress

sayla

[JimConlin]

I don't at the moment know of any designers doing traditional hull forms like that in trad. strip or strip composite.

The Dave Gerr book "Elements of Boat Strength" tries to lay out scantling rules. I'd start with that but seek out other designers, too.

[mmd]

Well...

If the proprietors of this fine place don't mind too much, I'll toot my own horn just a wee bit. I have done the engineering and design work to convert several large classic yachts to strip-cold-mould construction (Herreshoff, Crowninshield, Strange) and several traditional working craft (Cape Island lobsterboat, Northumberland Strait lobsterboat, Tancook sloop), and my own designs in the construction method. It is not polite for me to go on too much about my own work here on the forum, but I'd be pleased to share what little knowledge I have on the subject, with two conditions: I'm not here very much due to work demands so I'll only be able to visit once a week or so, and any questions about my own designs will have to be sent to me by private post or to my e-mail addy in my profile. If that's OK with with our hosts, I'll look forward to answering any questions you may have as best as I can.

[TerryLL]

Hey mmd,
I'm happy to see to posting here again. I wish you honored us more often with your advice.

[wizbang 13]

My mentor, Paul Johnson, designed several of his boats , the 28 and 34 , specifically for strip planking, but I think you know that.
Having built a few of them , and a few conventional older designs in strip planked, I would not hesitate, well, except to have a beer and build a model, to strip plank ANY small ( 2 thru 16 ton) vessel this way.

[JimD]

Greetings, mmd. Nice of you to stop by.

[skaraborgcraft]

I dont have a copy of Gerrs book, so i would be interested in MMDs advice and scantling observations in changing from carvel to strip/moulded,especially with regards to frames and stringers etc. Cheers

[mmd]

Skara (hope you don't mind the contraction of your handle), at this early stage of the conversation, there are few specific answers other than the dreaded "it depends". In broad strokes, a laminated frame is stronger, pound-for-pound, than a sawn frame and often nominally stronger than a steam-bent frame. Likewise, a hull of edge-glued wood strips is stronger than a mechanically-fastened plank-on-frame hull. So, if identical scantlings as the original construction is used, the hull is heavier and stronger than it needs to be, in most cases. And weight costs money. One of the great advantages of the equal-strenghth-for less weight paradigm is that we often would like to take advantage of modern technology that wasn't available back in the day, but this adds weight. Items like watermakers, holding tanks, battery banks, gensets, etc. all conspire to make the traditional design float deeper on her lines than originally intended, affecting performance. If you can shave off a few hundred pounds in the structure while maintaining original strength, then we can add the creature comforts that make our cruising more enjoyable. In some smaller hull forms, it is possible to omit framing altogether, freeing up space in lockers, additional headroom, etc. But - and I cannot stress this strongly enough, especially for vessels intending to carry family and friends father than a comfortable swim offshore - shaving weight by modifying structure is not something to be taken lightly (excuse the pun). IF you are going to do this, please make sure that you fully understand the nuances of boat structure & strength before committing your treasure and family's safety to the ocean's toss'd. Of course, my first advice would be to emply a competent and experieced designer to do the conversion or at very least, check your work.

In some cases, switching to strip-cold-moulding can allow the builder to address flaws in the original designs. For example, back in the 'teens and 'twenties, the racing yachts of the day had huge overhangs that "relaxed" after a few years, causing the bow & stern to hog and the hull to lose its shape. With judicious structural modifications and using stronger strip-plank construction, these lovely old hull forms can be recreated without the risk of the boat losing its shape for many years. Another advantage is that with a stiffer monocoque hull, higher rigging tensions can be achieved without the planking opening up, allowing rigs to carry more efficient modern sail shapes and sails made of higher-tech, less permeable materials.

[johngsandusky]

My ketch is a strip planked enlargement of a plank on frame schooner. She is somewhat overbuilt, but at 44 years old is very stiff, strong, and tight.

[potomac]

Thanks all. This information is good and in large part, is what led me to start this thread in the first place. The benefit of finding a designer who plans for the use of strip planking is that these questions are addressed. Strip planking appeals to me as opposed to cold molding as it seems less fussy, though it could be I am over-thinking the difficulty. It seems that strictly following the scantlings for framing and planking thickness will result in a hull that is incredibly strong, but maybe overly heavy and not taking advantage of the previously mentioned potential weight saving that allows for the modern technology mmd discussed.

I do not understand why this build method is not more popular. Maybe there are an insufficient number of builders (especially home builders) building boats in the 30'+ range. Cold molding seems much more protracted and fussy and requires two sources of different types of difficult to obtain wood. Carvel obviously has its advantages but also has its limitations. But both these building methods have several designers creating myriad designs. Maybe strip planking is a kind of middle ground between the two regarding framing, (The minimal of cold molding and the standard of Carvel) that creates questions/ problems?

The Paul Johnson boats are obviously lovely, but he does not seem to be active in the sense of being available to the home-builder for questions/ advice.

[potomac]

My ketch is a strip planked enlargement of a plank on frame schooner. She is somewhat overbuilt, but at 44 years old is very stiff, strong, and tight.

John- Do you have any pictures of your ketch? The particulars? Thanks- Aaron

[Farfalla]

MacNaughton Yacht Designs has produced a set of Scantlings Rules for each of cold-moulded, fibreglass, traditional carvel and sheathed strip plank construction methods.
These might be a good place to start so you could get some idea as to just what you're getting involved in. Then look for a designer, there are a few who do a lot of that work.

[skaraborgcraft]

MMD, no probs with the Skara. I just ordered a copy of Gerrs book for reference. Saving a few hundred pounds in construction for the typical heavy cruising boat that i would envisage using this construction for would not be an issue. Its a case of deciding how much of a saftey factor you may want built in,but at the same time,realising that there is no point having large frames and a skin that is lightweight,or a overly strong skin and small frames. I really like the idea of a clean interior and a dry bilge that a glued hull can give. I dont recall much in the way of bilge water in any of my plywood boats,but in the carvel and clinker,always water,maybe not much,but wet all the same. There seems to be quite different values on scantlings between instititions such as Lloyds Rules in comparison to other reference work. I think i would be inclined to take an average between published rules (more like opinions?). I have a friend with a hot moulded Fairy Jolly boat (i think) 3 layers of mahogany veneer and a mass of tiny ribs,a very involved build process,but no heavy timbers to deal with,but a very light and stiff hull, many still around after being built after the war,thats the extreme end of lightness and strength that glued construction can offer. Sorry if thats a bit of a drift from the strip plank. Selway fisher has a lot of designs in strip,some over 30 ft,he does not design for carvel, is at the end of the phone and a very helpfull chap. Cheers

[johngsandusky]

John- Do you have any pictures of your ketch? The particulars? Thanks- Aaron

Aaron, I'm bad with digital things. But there are some pictures of her on this site. Recently in my thread titled "Repair Unsheathed Strip Plank". If you PM me your email, I'll forward you some other photos. She is a 10% enlargement of the 1962 WD Knott designed schooner Aries. LOD is 39'6", LWL 35'3", beam 12'2", draft 5'6", displacement 16 tons (!). I think heavy displacement is a virtue in a cruiser, you really only lose light air acceleration. I was out last week close reaching in a gentle breeze, making six knots. WS is easily driven, in spite of a low sa/d ratio of 13, with 840sqft measured sail area.

[potomac]

John- Wow, what a boat. The repair sure looks remarkably good. Do you live aboard? The scope of your boat is certainly beyond any backyard building fantasies of mine. She looks huge to me and to be fair, Bruce's Woodwind looks quite big too.

The boat I am considering is a 7 ton boat and even that seems like quite a leap. More than Alden, I should probably be looking at a fishing/ working type hull- made to look a bit rough. The work many of you guys do, have done, are doing just boggles the mind. Don Kurylko's joinery on his cold molded hull is really something else

[johngsandusky]

Thank you. No, I don't live aboard, but have spent up to two weeks aboard, and plan to again this summer. The plan for the future is to winter aboard in the South. I certainly wouldn't want to build her alone.

[wizbang 13]

John- Wow, what a boat. The repair sure looks remarkably good. Do you live aboard? The scope of your boat is certainly beyond any backyard building fantasies of mine. She looks huge to me and to be fair, Bruce's Windsong looks quite big too.

The boat I am considering is a 7 ton boat and even that seems like quite a leap. More than Alden, I should probably be looking at a fishing/ working type hull- made to look a bit rough. The work many of you guys do, have done, are doing just boggles the mind. Don Kurylko's joinery on his cold molded hull is really something else

Woodwind
Do you have this seven tonner picked out yet? A model will answer many questions.
You are right about Johnson, He is alive but not "available".
A heavy disp boat , in general, can carry a greater proportion of weight with a smaller proportion of performance loss. It can be built heavier from the git go. Folks say you build a boat by the pound, I do not agree. A light disp boat is much, much more expensive per pound.

[potomac]

Sorry about that, Bruce. My brain is not what it once was and even then it wasn't that good. I hope I haven't miscalled her other places. If so, I apologize for that too. I think you know the high regard in which I hold her and your work, in general. Windsong sounds a bit effete for your taste, but if in search of a new boat's name- well, there you go. Now I must be off to read a bit more about James McMullen's Ronan and Yeadon's Large Food...or was it Big Dude?

[wizbang 13]

no prob

[potomac]

In my embarrassment, I forgot to answer your question. Alden's Malabar, Jr. is the one that started me thinking about this. Since then, I learned of the Malabar, Sr.. She is, I believe a similar boat, thought there were several iterations of the Jr. with pretty big changes in sail plan and even displacement.

The Sr. displaces 13,000 pounds, Carvel construction, 33' 4'' long, 9' 9'' beam, with a 5' draft. She is drawn as a Masthead Sloop.

The two boats have the same beam, but the Sr. has three extra feet of length, and standing headroom, for similar displacement. She, (the Sr.) doesn't seem roomy, but looked like enough for two adults and a kid to live aboard summers- as long as we continue to like each other. She also seems right at the outer edge of buildable for a home builder, at least this one.

The Jr. plans are available from our hosts for a nominal $150. Plans for the Sr. are considerably more from the organization that handles Alden's plans. They are certainly more substantial than the Jr. plans and I know they represent a fraction of the total cost of the boat, but they still constitute a large investment for me, so I haven't gotten them yet. I'm still trying to figure this all out.

Pictures:

[potomac]

Part of my hesitation, other than it seems a tremendous undertaking, is that logically it makes more sense to work with a designer who is living and can give you some support. Or at least to build a boat designed for this sort of construction like Paul Johnson. I like the looks of the Malabar Sr. and her rig looks relatively simple, that is part of her appeal. Looking at Bruce's five sails flying makes me think it's a bit beyond me.

[wizbang 13]

That 10 foot extra tallness of mast, compression rig (spreaders) and genoa sheets, these are things that scare me.

[potomac]

Hmmm...

Bruce, Have you ever had a look at any of the Ted Brewer boats, like the Cape Carib? How important do you think discourse with the designer is? It seems like you were working more or less alone, but you'd already done quite a bit of substantial building. Not the case here.

Want to be on retainer for questions? I might be able to find that generic beer.

[Cecil Borel]

I was also looking for strip planked construction in a 30-34' boat. I ended up building Kahuna, a Mark Smaalders design.http://smaalders.net/yacht_design/

[potomac]

What a lovely boat, Cecil. Is she done? Can you share anything about her construction, how long it took to build her, how it was to work with Mr. Smaalders, etc.?

[Cecil Borel]

I am near the end (I hope) of an 11 year project. I have been through 3 photo sites and don't have an easy album online right now. Mark has some of the build pix on his website. Mark has been great to work with, and has helped me along many times over the years. Her hull is strip planked over laminated ring frames, with 2 layers of veneer overtop, finished with xynole and epoxy. Deck and cabin are vacuum bagged fiberglass-core cell (my modification). Finished the mast last fall and have been working on the refrigerator cabinet and the companion way ladder most recently. Still need to wire, plumb, and build trim and cabinetry. Probably work on a hard dodger next. Feel free to contact me either through WBF on PM's if you have other questions. (I bet you will!)

[erster]

I am near the end (I hope) of an 11 year project. I have been through 3 photo sites and don't have an easy album online right now. Mark has some of the build pix on his website. Mark has been great to work with, and has helped me along many times over the years. Her hull is strip planked over laminated ring frames, with 2 layers of veneer overtop, finished with xynole and epoxy. Deck and cabin are vacuum bagged fiberglass-core cell (my modification). Finished the mast last fall and have been working on the refrigerator cabinet and the companion way ladder most recently. Still need to wire, plumb, and build trim and cabinetry. Probably work on a hard dodger next. Feel free to contact me either through WBF on PM's if you have other questions. (I bet you will!)

And a beautiful job that you have done too! But the time has come to wet it there feller.

[mmd]

Hi, Erster. I see on the weather reports that you guys on the mid-Atlantic seaboard are being roasted - stay hydrated and stay safe.

Scara, while many of my efforts in converting to strip-cold-mould construction has been motivated by weight reduction aims, there is also a cost savings - several hundred pounds of wood - in a heavily-built moderately-sized cruisiong boat maybe upwards of a ton of wood - costs money, too. Saving weight is also saving dollars.

Another point I'd like to make is about scantling rules: Know what vessel the scantlings rules were devised for. Herreshoff and Nevins, and to a lesser degree, Gerr (apologies to Mr. Gerr if I am misrepresenting him...) were devised to achieve adequate strength for rather lightweight racer/cruisers; I think I would be safe saying that all three would agree that the scantlings derived from their rules would not be adequate for a blue-water, long -distance cruiser or a commercial workboat. There are other rules that can be consulted, such as Lloyd's or Det Norske Veritas. Also, where unusual circumstanhces exist where rules do not address, such as local strengthening for dinghy davits and chocks, or windlass and winch bases, calculations via first-principle engineering formulae is the proper way to go. In any case, I would suggest, for the safety of yourself and the friends and family that you take to sea with you, that you consult with a naval architect, designer, or builder whom are experienced in the type and size of boat that you are considering building. Beyond peace of mind, such expenditure might also buy you lower insurance rates and lower material costs.

[skaraborgcraft]

MMD, im not sure Gerr would agree, i think he puts his scantlings on the side of caution to contstruct in his words "a superior vessel", (his book arrived today). In most of the hulls i have restored or fitted out,i have always over rather than underbuilt. However,on this new project i would like it to be strong enough,but not overly heavy,and also not too light so as weak. I normally use Lloyds, mainly because its whats to hand. I just responded to another post regarding Lindsay Lords lightweight strip plank construction,which im curious about,the original post was posted 6 years ago with no response! Its certainly an avenue worthy of further investigation,more so in my mind as no one seems to have any experience of it. Cheers

[beernd]

Hi, Erster. I see on the weather reports that you guys on the mid-Atlantic seaboard are being roasted - stay hydrated and stay safe.

Scara, while many of my efforts in converting to strip-cold-mould construction has been motivated by weight reduction aims, there is also a cost savings - several hundred pounds of wood - in a heavily-built moderately-sized cruisiong boat maybe upwards of a ton of wood - costs money, too. Saving weight is also saving dollars.

Another point I'd like to make is about scantling rules: Know what vessel the scantlings rules were devised for. Herreshoff and Nevins, and to a lesser degree, Gerr (apologies to Mr. Gerr if I am misrepresenting him...) were devised to achieve adequate strength for rather lightweight racer/cruisers; I think I would be safe saying that all three would agree that the scantlings derived from their rules would not be adequate for a blue-water, long -distance cruiser or a commercial workboat. There are other rules that can be consulted, such as Lloyd's or Det Norske Veritas. Also, where unusual circumstanhces exist where rules do not address, such as local strengthening for dinghy davits and chocks, or windlass and winch bases, calculations via first-principle engineering formulae is the proper way to go. In any case, I would suggest, for the safety of yourself and the friends and family that you take to sea with you, that you consult with a naval architect, designer, or builder whom are experienced in the type and size of boat that you are considering building. Beyond peace of mind, such expenditure might also buy you lower insurance rates and lower material costs.

What do you think about the method I am using for my build?
I use 4 layers of criss cros 6 mm planks.

http://forum.woodenboat.com/showthre...Goodchild-plan

Basicly the idea was born because of my lack of carpentry skills, but I am wondering if it would make sense for bigger designs, ( one of the advantages is that, contrary to large sheet of plywood, the strips are very easy to handle.

I use narrow strips so the even the largest gaps (plus or minus 2 mm) between layers can simply be filled up with epoxy, there is no need for vacuum bagging or the use of thousands of nails to force the veneers together.

Me being just plain curious to hear the opinion of a stripplank and could mould expert

[Mark Bowdidge]

G'day Beernd,
There's nothing wrong with what your doing, even as far as the gaps are concerned. With our Strip Plank composite designs, we use the same method, only we strip lengthwise using typically 30mm wide strips, leaving small gaps and then glue in between. As far as the size of teh strips are concerned, any larger than 30mm and you end up with a load of flat spots, which requires a lot of fairing and bogging later on.

Here's a couple of pictures of one of our designs, the Pro Tournament 21, that one of our clients is building to show what I mean. If you look carefully at the photo's, you'll notice that we use small plastic "Tile Spacers" to obtain an even spacing between the planks when fitting
Hope this helps

[gilberj]

I had a 30 foot double ended cutter of the Scandinavian style which was strip planked, without sheathing. Were I building I would do in the same way.
Years ago I had a chat with Bent Jesperson. At that point he was getting into cold-molding but figured he would rather traditionally build using carvel planking and wedge seam as it would be faster for him. He allowed that strip planing may be more efficient for a home builder.

[wizbang 13]

" If you look carefully at the photo's, you'll notice that we use small plastic "Tile Spacers" to obtain an even spacing between the planks when fitting"
Tile spacers between the planks,that is the craziest thing I ever heard of,(wink wink), at least since Paul Johnson taught me to lay wooden matches in "confectionists'" joinery,when using epoxy,um, 35 years ago.
That idea never went over too big here.

[keyhavenpotterer]

I've not seen it done that way before. I guess it means you can 'glue' it, all in one go, at the end when your done, rather than strip by strip too, which might be efficient.

Mark, done this way, do you just go easy on the outside epoxy fill then turn it right way up then fill the inner side between strips, rather than risk epoxy falling through between strips? And how do you get temp. fasteners out with epoxy troweled over?

What optimum blend of microfibres, silica or microballons do you use to get it viscous, strong and I guess fairable?

What's the optimum technique to getting it filled faired and unfastenened?

Ed

[Mark Bowdidge]

I've not seen it done that way before. I guess it means you can 'glue' it, all in one go, at the end when your done, rather than strip by strip too, which might be efficient.

Yes you do. The reason we advocate planking the boat dry first is because it's an easy way to ensure that the hull is fair and requires little sanding and bogging later on. Also, with the method we use, each plank is laid, allowing the plank to find it's natural "path" without any stressing of the plank or edgeset. By doing it this way, the only tool you need is a battery drill. That's it. No clamps or anything else.

Mark, done this way, do you just go easy on the outside epoxy fill then turn it right way up then fill the inner side between strips, rather than risk epoxy falling through between strips?

No, you fill the "gap" in one go, pushing the glue into the gap from the outside and any excess on the inside is simply wiped off and put back into your container, or if you find any voids..fill them. If you have someone to give you a hand, one on the outside and one on the inside telling you when to stop and cleaning the excess, you can rip through a boat like the Pro Tournament 21 in a couple of hours.

And how do you get temp. fasteners out with epoxy troweled over

The temporary bulkheads are made from MDF board (with the frame edges covered in plastic tape to stop the planks gluing to them - note the picture above) of which you then plank over and screw into with chipboard screws. When glueing the planks together, you simply glue each panel between the bulkheads, but not on the bulklheads themselves. Once the boat planks has been glued together, you can now remove all the chipboard screws from the boat and glue where the temporary frames are. Now the boat is just sitting, but not fastened down to the strongback/temporary frames. Now its just a matter of giving the hull a sand, then it's time to glass the hull. Once the hull has been glassed/ bogged/ faired and painted (typically the bottom plate only and a couple of inches onto the topsides plate), now you just lift the hull off the frames, roll it over, remove the remaining temporary frames (you've already removed nearly all of them prior to rolling) and then sand the interior fair ready for glassing. Then it's time to install all the bulkheads and longitudinals into position and tabb in. Its that easy

What optimum blend of microfibres, silica or microballons do you use to get it viscous, strong and I guess fairable?

50/50 cabosil and microballoons. Mix to a peanut butter consistancy

You can see the whole build process here:
http://bowdidgemarinedesigns.com/For....php?f=18&t=55

Hope this helps Ed
regards
Mark
------
www.bowdidgemarinedesigns.com

[keyhavenpotterer]

Cheers Mark. Great lookin boats by the way....

[beernd]

I've not seen it done that way before. I guess it means you can 'glue' it, all in one go, at the end when your done, rather than strip by strip too, which might be efficient.

Mark, done this way, do you just go easy on the outside epoxy fill then turn it right way up then fill the inner side between strips, rather than risk epoxy falling through between strips? And how do you get temp. fasteners out with epoxy troweled over?

What optimum blend of microfibres, silica or microballons do you use to get it viscous, strong and I guess fairable?

What's the optimum technique to getting it filled faired and unfastenened?

Ed

Looks absolutely brilliant for a woodbutcher like me, I will use 30mm nails as spacers, since I am clamping the planks for the second layer with these nails.

Thanks for the tip

[kbowen]

MacNaughton Yacht Designs has produced a set of Scantlings Rules for each of cold-moulded, fibreglass, traditional carvel and sheathed strip plank construction methods.
These might be a good place to start so you could get some idea as to just what you're getting involved in. Then look for a designer, there are a few who do a lot of that work.

I am working on a 26' Mackinaw boat, adapted to strip- composite. I got scantling recommendations from the Gougeon Tech department, and from MacNaughton, Gerr, Gartside, & Wyman, and the recommendations were all over the map. Once I stopped being frustrated, I stared to see the breadth of this data as a spectrum, and one can choose their place on that map because you are putting your life in your own hands no matter what you do. The recommendations I got for strip thickness ranged from 9/16" to 1 1/8" with various combinations of fiber and epoxy. Working with David Wyman I have settled on the upper-middle end of the spectrum because I intend to beach the boat occasionally. The lines that Chapelle drew in ASSC put the boat down at about #6000 and I am doing 7/8" WRC with 6 + 6 oz of glass inside and out, and maybe another layer below the WL. fwiw, I understand that strength in a tensile-skin structure goes up as the square of thickness; ie twice the thickness is 4x the strength.

[Mark Bowdidge]

We engineer all our designs to ABS or Lloyds

[kbowen]

We engineer all our designs to ABS or Lloyds

Which I have heard about, and I think I pursued for a while, but at some point I hit the classic MEGO point, (My Eyes Glaze Over)

[Mark Bowdidge]

7/8" WRC with 6 + 6 oz of glass inside and out, and maybe another layer below the WL.

Wow, that's pretty thick. I'd go a thinner plank and then use 400-450 gm Double Bias. Far stronger

[kbowen]

Wow, that's pretty thick. I'd go a thinner plank and then use 400-450 gm Double Bias. Far stronger

It is a #6000 boat. The original scantlings are unknown, but Chapelle drew the rabbet at 3/4" for traditional construction. Gougeon recommended 3/4" WRC with the layup I reported. David Wyman would have preferred 1". Attached is the address of my blog with the full run-down of the Scantling recommendations I received. I would be interested in your feedback on that data.

http://blogs.latinschool.org/adrift/...ng/scantlings/

Thanks for your input,
Ken

[Mark Bowdidge]

I'm PM you, as I don't think it would be appropiate to post something on here.
Also, when engineering to either Lloyds or ABS, it's not just a matter of one, two, three... there's my answer as per the scantling rules mentioned above. There is a lot more going on in regards to info required and how it's going to be applied to the said design.

[skaraborgcraft]

Mark, in your opinion, what is the advantage of your strip plank/gap/bog system over bead and cove? I can understand time factors in commercial buisness may outweigh the trade costs of the amount of epoxy used,but whats the argument in favour for the amatuer builder? Cheers

[Mark Bowdidge]

Mark, in your opinion, what is the advantage of your strip plank/gap/bog system over bead and cove?

G'day mate,
In the past , when we used to build commercially, we built 2 catamarans (a 35fter and the other was a 48fter) using the bead and cove method. What a waste of time and money in my opinion and we never used it again. Bead and cove, in order for it to work out properly, needs long straight runs with no twist. Once twist sets in, now the plank needs to be "forced" into postion, resulting in flat spots and the like, which no doubt requires a lot of sanding and bogging to bring fair. The only way to really get around it , is to use "square" planks in section. However, where the scantlings may call for 1/2" of 3/4" plank in thickness, constructing a boat in 1/2" of 3/4" square section planks is going to take forever to plank and no doubt, a lot of glue. So, to get around this problem, we all want to use rectangluar planks to speed the process. However, by using rectangluar planks and planking a boat in the normal fashion where each plank follows the next, lends itself to other problems...planks twisting resulting in flat spots. No doubt this will require a lot of sanding and filling with bog to get a fair hull. Also, it requires a lot more work to actually create the hull in the first place.

Here's a couple of photo's of Deans pervious build (not one of my designs), where he planked in the normal fashion:

You can either plank like this, putting on a few planks per day, with clamps etc holding and forcing the planks in position while the glue sets...





Or...you can plank like this. It's up to you








When planking hull, no doubt you have the main master plank which is laid first (see above). However, in the process of planking, allowing each plank to "find it's own way naturally", you will find that a second or third master plank will be required. Well, that ok, because any gaps that do occur are now filled with "stealer planks", each being laid naturally with no twist. This is where "bead and cove" falls down . Bead and cove planking requires that each plank follows the other, whereas with our method, the planks are not all following each other, but are allowed to "find their own path" with no twisting, resulting in a super fair hull right from word go.

I can understand time factors in commercial buisness may outweigh the trade costs of the amount of epoxy used,but whats the argument in favour for the amatuer builder?

I have seen mentioned in other forums where people mention that our method use's a lot of glue and would be expensive (actually, it's 50/50 cabosil and microballoons). Well, in reality, it doesn't and isn't. If you cost "straight" timber as opposed to bead and cove timber and compare that to around the 6kg of glue mixture that Dean used to glue the planks into positon with his Pro Tournament 21, you tell me which is cheaper. Also, by comparing the photo's above, which method do you think would be a quicker build ?

Anyway, that's not only my opinion, but also comments made by our clients as well.

Here's a "you tube" link to the strip planking DVD that we provide, as a part of all our strip plank composite plans. It's only an intro clip, however I hope you enjoy it:
http://www.youtube.com/watch?v=xTA9J3-w4U0

Hope this helps

----------------
Mark Bowdidge (MRINA)
www.bowdidgemarinedesigns.com

[eminence front]

I'm no master builder here, and for that matter I haven't even started to build yet, as I'm still in the research stage. I happened upon Mark's procedure a while back, and as far as I'm concerned, It appears to make the most sense, both in simplicity and economy. I admire Mark in the utmost way, as he seems to be well versed and a gentleman to boot. He has given alot to the craft and seems to continue. He is selling a video of this process and I'll be purchasing a copy soon. Thanks Mark for helping others, often at no cost. These pics he has posted as well as his knowledge being paid forward are worth their weight in gold. Just my 2 cents.

[skaraborgcraft]

Mark, thanks for the detail reply. I had a look through the first 10 of 80 pages on Deans blog, and recall him saying he had used 2 20kg tins. I dont know how much he used in total?

This is just new, and without epoxy would not be a valid build method. Im not the greatest lover of working with epoxy, but if i have to work with it,it has to be with a system that makes the most of its key advantages, and your system seems to do just that. I think respect is due to those that can think outside the box and come up with workable alternatives. I can definately see myself trying this out at some point down the road. Cheers

[Mark Bowdidge]

Mark, thanks for the detail reply. I had a look through the first 10 of 80 pages on Deans blog, and recall him saying he had used 2 20kg tins

The 2 x 20kg drums stated, is for:

Construction of the bulkheads
Construction of the longitudinals
Construction of the transom (laminate plywood)
Glueing the planks together when planking
Glassing the hull with 450 gm Double Bias (bottom plate requried 2 layers)
Bogging the hull ready for highbuild/paint.

Overall that's not bad for a hull that's 21 ft long and 7ft-7in wide, capable of 40 kts as a serious offshore 25 degree @ transom design . Remember though, this is a true composite boat, not a timber boat per say. You'll find no screws/ nails, timber (except for the hull skin itself)... nothing except plywood, paulownia and glass/epoxy. That's it. And as far as epoxy is concerned, all up the boat, now finished, has used 200kg of epoxy, where everything is glassed and epoxy coated. All up finished with 140 HP outboard/ fuel (200 liters), personal gear etc etc, her towing weight (including trailer) is approx 1500 kg ( 3306 lbs).

Anyway, just thought I'd throw up options in regards to different building techniques. What you do is totally up to you. We just do things here in Oz...differently

hope this helps

[keyhavenpotterer]

I really like that its glued all at the end. Here in very temperate climes, with cold dark damp winters, you could plank up the hull easily in the winter 'dry' with your tile spacers, waiting for August and a month of warm weather and long evenings, then glue it up in a few sessions when the weather is optimum. Less chance of being bogged down twisting a garboard on a dark night in a cowshed or trouble gluing with cold overnight temperatures when boat building after normal working hours.


Ed