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heavyweather
07-12-2014, 07:49 PM
I have redrawn the hull in CAD and like some other non-cad boats some of the points from the table in the book [Boatbuilding for Beginners (and beayond)] where off some 6-20mm.
I started by taking the points for the wale and drawing a curve with one control point through these points using the bowpoint, the point above the lowest bottom point (at 8') and the point at the transom for fixed points.
Then I extruded this curve down at the angle the transom runs down the sides. The sides don't wind but go down in a straight line.
I then drew the rocker curve, extruded that one and cut the sides with the bottom plane. The resulting curve between the two panels was checked against the points from the table. Again the points at 4' and 6' are off some millimetres. To correct that I would need more control point resulting in an unfair curve (maybe not really unfair but for me 2 control points feel like cheating the curvature flow). In third picture you can see how my curve runs between the points from the table and that the points are jumping left and right. I can get it near to 6mm error with a second control point. Could be that I have just misread some of the little numbers in the table or that I did something wrong. Maybe that is the reason why people loft in the first place? Are lines always met on the mm when lofting a table? I wonder if it just checks out if you use the pattern included? Maybe my bad as I did not bother to buy the plans (the book was available in Europe and I had it in 2 days) because shipping would take about 3 weeks and I really don't have the time to wait and I don't plan on building the boat like in the book anyway. Ok...now I will try to figure out how to do it instead.

http://thumbnails109.imagebam.com/33855/2e5b90338548260.jpg (http://www.imagebam.com/image/2e5b90338548260) http://thumbnails109.imagebam.com/33855/87129a338548270.jpg (http://www.imagebam.com/image/87129a338548270) http://thumbnails110.imagebam.com/33855/dca108338548274.jpg (http://www.imagebam.com/image/dca108338548274)

heavyweather
07-13-2014, 05:29 PM
I extruded the second try now a curve with two control points. Now I am only off 13mm instead of 22mm at the worst. Does it make any difference? Probably not. Should I go with the curve better fitting the points from the table or use my 1 control point curve? I don't know. What would you do?

http://thumbnails111.imagebam.com/33872/c7164b338718940.jpg (http://www.imagebam.com/image/c7164b338718940)

John Bell
07-14-2014, 07:19 AM
Why are you doing this? A bunch of these have been built according to plans and they worked out just fine.

In practice, you cut out the topside panels, the stem, the transom and intermediate bulkheads/temporary forms first. You then take the boat "3-D" by springing the topsides around the forms/bulkheads. Apply chine logs and gunwales and then you take the shape of the bottom and decks right from the boat. If it is a few mm off the the plans, so what?

FWIW the handful of boats I've seen built to these plans all look to have pleasant, fair curves to my eye.

heavyweather
07-14-2014, 03:15 PM
I need to do something new.

First I need to tidy up my basement shop to fit in the mold. I drew the plans to get the lines for my mold, it will be smaller than the actual hull. The 4,26m will just barely fit in. Maybe I should have chosen a 12' design in the first place.

http://thumbnails109.imagebam.com/33887/b2d29c338866370.jpg (http://www.imagebam.com/image/b2d29c338866370)

heavyweather
07-15-2014, 05:41 PM
I am still drawing the boat.
I plan on cutting it flat on top. From the pictures I found it appears that it does not need to be that deep up front.
http://1.bp.blogspot.com/-SdTAIyohpgc/T_9wOZ7yclI/AAAAAAAABAw/ZSKbGJ14PRc/s1600/024+-+Copy+(2).JPG

I can cut away at least 20cm resulting in a much flatter sheer line. I guess it won't matter at all. To get into Laser territory I would have to cut down about 35cm.

heavyweather
07-15-2014, 05:51 PM
So this will be my new sheer-line.

http://thumbnails111.imagebam.com/33910/804b2b339092386.jpg (http://www.imagebam.com/image/804b2b339092386)

It will also save some weight on some of the frames...not much though.

heavyweather
07-15-2014, 06:28 PM
There will be 2 openings in the transom and the ruder mounting slide will be inside the hull. Maybe there will just be a tube for the ruder to pivot inside the hull.

http://thumbnails111.imagebam.com/33910/d64faa339094570.jpg (http://www.imagebam.com/image/d64faa339094570)

heavyweather
07-16-2014, 10:32 AM
In the end I am looking for a structure that is fairly rigid without the hull. So I have decided to build a jigsaw puzzle again like I did with my last boat. I do not want to overbuild again so I am adding parts as I need to.
There will be one spine piece first along the bottom defining the rocker alongside which the daggerboard will be located.
Two 20mm round fir stringers for chines. The bulkheads (6-8 from plywood square boards 15cm high like on this GIS) (http://1.bp.blogspot.com/-CTs4FrHFiqQ/TvC5k1_1q8I/AAAAAAAAAM4/j9KEktDAzJ4/s400/mid+seat.JPG) with will slot into the spine.
If I need to I will add "side-spines running flat around the sides slotted in the bulkheads. Ladder-work flooring will further help to stiffen up the structure.

The slotted technique (http://sybaritica.files.wordpress.com/2013/06/bounty-002.jpg) is just like building the mold for the Shellback dinghy (http://1.bp.blogspot.com/_Zmd5FieM3f0/SbCt4nH4vHI/AAAAAAAAC28/yH_oDmUsecA/s320/shellback_20090305_0353.JPG) and a good way for me to avoid building a temporary mold.

I will probably straighten/tilt the transom so that it meet roughly perpendicular with the waterline. The boat sits so hight that it really does not matter and I will lose some length and weight without loosing anything else (it does not look like a Mayfly hull any-more anyway).

David G
07-16-2014, 11:16 AM
Well... I hope you're having fun.

Gerarddm
07-16-2014, 01:37 PM
With all your modifications, it is no longer a Mayfly 14. It is now a Heavyweather 14. As David G said, have fun.

cracked lid
07-16-2014, 06:20 PM
I'm genuinely curious as to why you're putting this much work into tweaking a Mayfly 14 into something different. I always thought one of the principle advantages of the design was that it was made to be built with a minimum of time and expense.

heavyweather
07-19-2014, 07:17 PM
http://thumbnails110.imagebam.com/33994/f4795c339937978.jpg (http://www.imagebam.com/image/f4795c339937978)

Some of my first design ideas. The "spine" will be broken down into pieces. No piece can be longer than 120cm.
The maststep will be the front of this Cross which is supposed to stop the hull from winding and also serves for the stations forward.
Everything should slot together.

heavyweather
07-19-2014, 07:31 PM
I like to think that someday I will own my own huge lasercutter. I would also be content with a huge CNC router.
Maybe I'll go and cut a model of my hull here http://lazzzor.soup.io/
I love this stuff that slots together to form something three dimensional.
I will definitely do a scroll saw model first.

heavyweather
07-20-2014, 06:35 AM
I'm genuinely curious as to why you're putting this much work into tweaking a Mayfly 14 into something different. I always thought one of the principle advantages of the design was that it was made to be built with a minimum of time and expense.

The boat is skegless, the size is almost right but I would not get the completed hull out of my basement. There are 3 corners and a staircase. Time and money do not matter of course. I don't know if I can manage to finish before winter or if it will work at all but I got my sailing pram for this summer. The problem is that no such boat can be bought...

heavyweather
07-24-2014, 09:33 AM
I am away from my pc and contemplating about the design.
Things would be easier if I would revert my rules to "no part must be longer than 207cm.
All parts could still be done in my basement, assembly would be easier and I might end up with less weight.
The spine could be boxlike 5cm sided. I could save some stations also, I was planning on 9-12, maybe 7 will do.
The cross pieces could also be made of one part.

I just need more planning. Once everything is drawn up It should be cut and assembled in 3-4 days.

heavyweather
07-24-2014, 05:13 PM
I did some work today.
I really want to start cutting so drawing and thinking is getting hard.
This is the structure so far. The side parts are missing and I do not know if I want one additional spine on both sides. I could also use the floorboards to stiffen the whole structure by mounting them on the spines and on the frames.
Where should I mount the mastpartner? obviously it will be between the frame near the maststep and then I may span it down to the frame forward and the frame aft. The gunnels are not really part of the "superstructure" but will help to hold the rocker in shape.
I am pretty pleased with the idea of the diagonal maststep members. I will soon start to build a model, put a mast in and try to wind it around.

The 12mm phenol coated ply I am using weights between 7 and 9kg/m², depending on the quality (mixed in Asian redwood layers or East-European birch).
All the ply parts in this model amount to 2.28m² now. I want to stay under 60kg.


http://thumbnails111.imagebam.com/34091/9cf554340905076.jpg (http://www.imagebam.com/image/9cf554340905076)

heavyweather
07-26-2014, 06:27 PM
Here is my latest progress.

I am not that happy with the diagonal frames any more. They would need to much slotting at the crossing. Crossing three slottet parts is probably a bad idea.
Any ideas on that?
I may have a solution for the stiffness problem. The bottom could be made of 4 cassettes that are mounted between the spines and under the bulkheads. I can build them preformed and they could also form the chines. There would be blocks between the sticks....all rounded inside with the forstner bit. Should look pretty nice. I am still working on how to fix them to the frame. They com from below and must be fixed to the sides of the spines and to the bulkheads. maybe by bolts, hooks or straps. Something cheap and available.
They would be 180cmx25cm in size...which would be OK I guess. I'll end up with a pretty huge heap of bits anyway.
I have also drawn the daggerboard parts by now.
The round diagonal thing could be bamboo for more strength.



http://thumbnails112.imagebam.com/34131/99ab00341307447.jpg (http://www.imagebam.com/image/99ab00341307447) http://thumbnails111.imagebam.com/34131/c53543341307451.jpg (http://www.imagebam.com/image/c53543341307451)

heavyweather
07-27-2014, 05:37 PM
Two new options.
I want a cassette ruder like on the GIS.
I need to find a way to mount it.
The first idea is screwing it through the transom (safety belt hinges), the second option is to use a rod and pivot it inside the hull.


http://thumbnails112.imagebam.com/34152/1b52af341514466.jpg (http://www.imagebam.com/image/1b52af341514466) http://thumbnails109.imagebam.com/34152/088677341514483.jpg (http://www.imagebam.com/image/088677341514483)

heavyweather
07-30-2014, 07:30 AM
http://thumbnails111.imagebam.com/34200/373998341991688.jpg (http://www.imagebam.com/image/373998341991688)


My last update.
What do you think?

flo-mo
07-30-2014, 08:34 AM
I am wondering why there is so little feedback to all your efforts.

Maybe it is because at first sight it is not recognizable that you are constructing a folding boat and also in the thread title there is no reference to this fact.

heavyweather
07-30-2014, 08:47 AM
:p. Nooooooo
I didn't want to give it away so soon.
Some have known all along anyway :)

OK...it will pack. I am planning a 400g PVC hull Tom Yost style that will zip over the bow and will probably be secured with bungee aft.

I already found a Sattler at Erzherzog Karl Straße that is selling PVC or even can make the skin. There is another one at Gumpendorfer Straße.
I am also trying to get a German seller to mail me a Hart Capri Faltjolle.

heavyweather
07-30-2014, 08:52 AM
With all your modifications, it is no longer a Mayfly 14. It is now a Heavyweather 14. As David G said, have fun.

I should call it Sunnyweather with that lowered sheer.

flo-mo
07-30-2014, 09:12 AM
So you wanted to rise tension until full disclosure ? I did not get that.
Sorry I gave it away.

SNAPMAN
07-30-2014, 10:15 AM
I don't think you will need diagonal frames. The Nautiraid and Klepper Master folding sailboats strictly use stringers and frames. If you haven't already, they might be a good reference in terms of how they are framed.

The Nauriraid 300S (good pictures in the 2013 brochure) appears to have only 3 cross frames plus transom, a lot less parts than the Klepper folder I owned 20 years ago....

There are pictures of the Klepper scattered around as it hasn't been made for decades, if you can't find them, I can post a few later.

heavyweather
07-30-2014, 10:18 AM
Don't be sorry, it was obvious anyway that something was not right here ;)


What do you think? I am already around 40kg. The difference to the Klepper Passat or similar is that I don't use that much metal, they even had metal ruderblades and daggerboards.
I am still not sure if I have enough strength in the frame. The skin will help a little I guess.
Maybe I should just go ahead and start cutting...move it back to the design forum or try harder to buy an old boat :)

heavyweather
07-30-2014, 10:22 AM
I don't think you will need diagonal frames. The Nautiraid and Klepper Master folding sailboats strictly use stringers and frames. If you haven't already, they might be a good reference in terms of how they are framed.

The Nauriraid 300S (good pictures in the 2013 brochure) appears to have only 3 cross frames plus transom, a lot less parts than the Klepper folder I owned 20 years ago....

There are pictures of the Klepper scattered around as it hasn't been made for decades, if you can't find them, I can post a few later.


I have found plenty of old boats from Klepper, MTW, Hart an others. They used to wind/warp badly so I guess cross members would have helped.
I have some doubt about my plan because all the old boats are more or less built the same way.
There are also a lot of Russian boats mostly made of aluminium.

skaraborgcraft
07-30-2014, 10:50 AM
Interesting concept. As FloMo pointed out, if the thread title was changed to skin on frame folding 14ft skiff,or something similar, you would definately have got a lot more attention. I for one didnt know why you was changing so much off a design that already works.....now i see...

SNAPMAN
07-30-2014, 04:38 PM
If twist is the issue, you might consider tension members, perhaps 1" webbing run diagonally, attached in an X pattern, though one X run at about 45 degrees might suffice. The ends could be tensioned with lacing so the frame maintains alignment.

heavyweather
07-30-2014, 04:50 PM
Here is my other thread I started for finding a design. (http://forum.woodenboat.com/showthread.php?166868-which-sailboat-would-make-a-good-folding-boat-of-around-4m-loa&highlight=)
Originally I wanted to build something like the Nautiraid 300s but it would have been too long in one part.
I then collected more information on a German board - there is plenty of information on Faltjollen in German - and found some more homemade Russian boats, all made from metal.
Russian 1 (http://translate.google.com/translate?depth=1&hl=en&ie=UTF8&prev=_t&rurl=translate.google.com&sl=auto&tl=en&u=http://iv70.narod.ru/IV4/Shkentel/SH.html)
Russian 2 (http://translate.google.com/translate?depth=1&hl=en&ie=UTF8&prev=_t&rurl=translate.google.com&sl=auto&tl=en&u=http://iv70.narod.ru/IV4/SH_B/Karkas/IAMAL.html)
The second builder used a box keel to get a rigid structure/stop the boat from warping.
I was also thinking to run wires or ropes diagonally.around the hull.
I am less worried about heeling forces, the bulkhead should take care of that (I had a rig on the SOF Mippet we built at school and the fairly weak boat and mast mount where no problem.)
The second boat even looks to be made for production but I can't find any other folding sailing dinghy apart from the 300S on the market.
I can only guess but there seems to be no need for a folding sailing dinghy at least in the states. On one other thread someone was looking for a boat he could transport by bike.
Nothing homebuilt in that direction apart from Tom Yost's folding kayaks.

I will try the gunnel part ladder thing unbent. The curves seem to be nothing compared to my last three boats and I thing a little tension can't be bad. I am only worried about installing them one after the other.

heavyweather
07-30-2014, 05:00 PM
I am closing this thread.
Copied it to rename it.
http://forum.woodenboat.com/showthread.php?180483-Mayfly-14-MOD-skin-on-frame-folding-14ft-skiff