Author Topic: Hello from Finland (and a question...)  (Read 1360 times)

Online Pekka

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Re: Hello from Finland (and a question...)
« Reply #15 on: March 09, 2024, 03:56:58 AM »
Correct. Instead of bending and laminating two 6mm panels I'm hoping to be able to bed a single 9mm panel. I realize it might be a challenge. I will do the "bookmatch and fold open" -method as in the video jallii referenced earlier.  If they don't bend "dry" the I might try with heat or steam or both. Worst case scenario is that I will have to buy new plywood for the bottom and will end up with plenty of quality ply to use in the interior of the boat. While I am on a restricted budget I think that either way this experiment is worth doing. The long lengths of ply are not that much more expensive than shorter ones. Also the surface quality is way better.

According to plywood manufacturers data the 9mm birch ply is about the same strength as 12mm "soft wood" ply (pine or fir for example). 3mm thinner hull naturally has an effect on the stiffness when the layers of glass are closer to each other but the additional stiffness of the birch ply should offset that. I am planning to put one extra layer of glass to the bottom and add longitudinal stiffeners between the stringers and sides and stringers and fairbody (four in total). This way I should end up with about the same weight as with 12mm panels.

Using feet and inches and fractions seems to be fine until I need to do calculations :D Then I'll just resort to a calculator and flip everything to metric. When reading the book it was first really frustrating when in the same sentence there would be the same dimension in feet and then in inches. For example instruction to cut a 8' by 4' panel to 48" by 48" pieces. Not 4' by 4' but 48" by 48".  :o I eventually realized that when you learn something as a kid then it just is natural and you don't even think about it. Then writing a sentence like that makes total sense. Also, "ton" is 2000lbs? Dude! For me a ton or "tonni" in Finnish has always been a synonym for 1000.

Pekka


You might remember that in the forward part of the bottom panels you're not bending the 1/2" (12mm) ply rather the one piece of the 1/4" (6mm) ply that's scarfed to the 1/2" ply. After seeing how flexible the 3/8" ply (9mm) ply is that's used for the topsides I'd be a little skeptical that you're going to be able to get it to bend enough to make the forward section of the bottom. It'd be interesting to try. The absolute best way to try would be by bookmatching and stitching them together then opening them up. Maybe a bunch of stitches close together for the first 8ft and use wire for the stitches. I guess a question might be, what happens if it doesn't work? You've bought a bunch of ply, now what? Another thing to maybe think about in using 9mm for the bottom is while there is a lot of shape in the first few feet there is none for the rest of the length, so you'll likely be adding stringers and frames for stiffness.
As far as starting with long lengths of ply. It'd be cool if you can and it's not too expensive, but I made a scarf cutting jig and cut 12 scarfs in a day. Scarfs aren't that big a deal.
If you're use to working in metric, I'd just convert the dimension in the book. You could probably go through the whole book and convert what you need in a couple of hours. It'd save you the misery that is fractions.

Offline Kobuk

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Re: Hello from Finland (and a question...)
« Reply #16 on: March 09, 2024, 09:39:41 AM »
I think it takes a special kind of masochist to deliberately want to convert back and forth between metric and english measurements! :P

I'm following along with great interest.  By my experience, it is certainly out of the question to bend 12mm Hydrotek Meranti at the bow...6mm resists admirably.  It will be interesting to see if it can be done with 8mm birch.  I doubt it's practically possible, but if so i'm sure it will require a much stronger stitching material than either mechanic's wire or zip-ties.  Please post some photos as you go along!
« Last Edit: March 09, 2024, 09:41:32 AM by Kobuk »
https://www.fishyfish.com/boards/index.php?topic=5536.0
Started: 3/2019
Flipped: 6/2019
Floated: 6/2020

Offline KenB

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Re: Hello from Finland (and a question...)
« Reply #17 on: March 13, 2024, 09:42:00 AM »
I did a widebody with 3/4 bottom and 3/8 bow sheets... no issues bending 3/8 ply. 9mm will be fine, but make sure the back panels are 18mm then?

You might remember that in the forward part of the bottom panels you're not bending the 1/2" (12mm) ply rather the one piece of the 1/4" (6mm) ply that's scarfed to the 1/2" ply. After seeing how flexible the 3/8" ply (9mm) ply is that's used for the topsides I'd be a little skeptical that you're going to be able to get it to bend enough to make the forward section of the bottom. It'd be interesting to try. The absolute best way to try would be by bookmatching and stitching them together then opening them up. Maybe a bunch of stitches close together for the first 8ft and use wire for the stitches. I guess a question might be, what happens if it doesn't work? You've bought a bunch of ply, now what? Another thing to maybe think about in using 9mm for the bottom is while there is a lot of shape in the first few feet there is none for the rest of the length, so you'll likely be adding stringers and frames for stiffness.
As far as starting with long lengths of ply. It'd be cool if you can and it's not too expensive, but I made a scarf cutting jig and cut 12 scarfs in a day. Scarfs aren't that big a deal.
If you're use to working in metric, I'd just convert the dimension in the book. You could probably go through the whole book and convert what you need in a couple of hours. It'd save you the misery that is fractions.


Seems like a very sensible plan... You certainly save a lot of time with those long panels.
That saves you a lot of time. Is it worth the money... I have at some time considered the same approach. At that time I came to the conclusion that it would probably be too expensive to get those long panels made, and never went further to ask for quotations. 
 
I also noticed that you are using 9mm birch ply instead of 12mm fir ply. 9mm will also make bending the bow plates a lot easier.  Are you planning to increase webbing between the stringers or increasing glass content to compensate, or are you only relying on the comparative strengths of ply.  I think the 9mm might be sligthly too thin for CE demanded scantlings as Tollmans only have longitudinal stringers.  What about adding longitudinal battens between keel and stringer and stringer and chine to the inside of bottom plates. They would compensate for your thinner bottom plates reducing vibrations/flex.  Simply make the bottom normally. Then glue the battens and cover them with epoxy+glass.  Thats a simple

I once saw a video about Anthony Lyndaker making the bottom panels by simply having both bottom panels on top of each other, cut to form and tied together at the keel, and simply opened as a book. The form of the panels took care of the bending automatically. Much easier than Renns method.
https://www.youtube.com/watch?v=uIb2Km8JHW8

I originally found it hard to visualize any dimensions in imperial system. It has taken a long time to get accustomed to them to some degree.  Perhaps you simply need to dive into the imperial world fully and not try to translate at all.  Your approach is simple and effective.

About thin veneer products:
Have you asked them?
https://koskisen.fi/tuotteet/ohutvaneri-ja-viilut/ohutviiluvanerituotteet/
best,
KenB

"HOW CHEAPLY CAN A TOLMAN SKIFF BE BUILT AND JUST HOW  MUCH IS SACRIFICED IF COST IS THE PRIME MOVER?"
- Bruce Armstrong   

"I can tell you that either a nice BFT or a big YFT is an absolute riot on a Tolman. The boat is so light it's like the old man and the sea..."
- Dave Nolan (RIP)

Offline KenB

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Re: Hello from Finland (and a question...)
« Reply #18 on: March 13, 2024, 09:48:37 AM »
Nope, already wrong... if you scarf 2x 48" pieces they will be shorter than 8', by the size of your scarf.  This is a great example of the kinds of headaches that arise from trying to "improve on" or "modify" whats in the book. 

I built a Gloucester gull (bolger light dory) in Japan. I converted everything to metric (no yard sticks), but if I were to do it again, I would just keep everything imperial. Too many chances to screw things up.

1000 kg is 2200 lbs, so pretty close.

Also, I would not do less than 1/2 ply for the main bottom panels in the rear.

Correct. Instead of bending and laminating two 6mm panels I'm hoping to be able to bed a single 9mm panel. I realize it might be a challenge. I will do the "bookmatch and fold open" -method as in the video jallii referenced earlier.  If they don't bend "dry" the I might try with heat or steam or both. Worst case scenario is that I will have to buy new plywood for the bottom and will end up with plenty of quality ply to use in the interior of the boat. While I am on a restricted budget I think that either way this experiment is worth doing. The long lengths of ply are not that much more expensive than shorter ones. Also the surface quality is way better.

According to plywood manufacturers data the 9mm birch ply is about the same strength as 12mm "soft wood" ply (pine or fir for example). 3mm thinner hull naturally has an effect on the stiffness when the layers of glass are closer to each other but the additional stiffness of the birch ply should offset that. I am planning to put one extra layer of glass to the bottom and add longitudinal stiffeners between the stringers and sides and stringers and fairbody (four in total). This way I should end up with about the same weight as with 12mm panels.

Using feet and inches and fractions seems to be fine until I need to do calculations :D Then I'll just resort to a calculator and flip everything to metric. When reading the book it was first really frustrating when in the same sentence there would be the same dimension in feet and then in inches. For example instruction to cut a 8' by 4' panel to 48" by 48" pieces. Not 4' by 4' but 48" by 48".  :o I eventually realized that when you learn something as a kid then it just is natural and you don't even think about it. Then writing a sentence like that makes total sense. Also, "ton" is 2000lbs? Dude! For me a ton or "tonni" in Finnish has always been a synonym for 1000.

Pekka


You might remember that in the forward part of the bottom panels you're not bending the 1/2" (12mm) ply rather the one piece of the 1/4" (6mm) ply that's scarfed to the 1/2" ply. After seeing how flexible the 3/8" ply (9mm) ply is that's used for the topsides I'd be a little skeptical that you're going to be able to get it to bend enough to make the forward section of the bottom. It'd be interesting to try. The absolute best way to try would be by bookmatching and stitching them together then opening them up. Maybe a bunch of stitches close together for the first 8ft and use wire for the stitches. I guess a question might be, what happens if it doesn't work? You've bought a bunch of ply, now what? Another thing to maybe think about in using 9mm for the bottom is while there is a lot of shape in the first few feet there is none for the rest of the length, so you'll likely be adding stringers and frames for stiffness.
As far as starting with long lengths of ply. It'd be cool if you can and it's not too expensive, but I made a scarf cutting jig and cut 12 scarfs in a day. Scarfs aren't that big a deal.
If you're use to working in metric, I'd just convert the dimension in the book. You could probably go through the whole book and convert what you need in a couple of hours. It'd save you the misery that is fractions.
best,
KenB

"HOW CHEAPLY CAN A TOLMAN SKIFF BE BUILT AND JUST HOW  MUCH IS SACRIFICED IF COST IS THE PRIME MOVER?"
- Bruce Armstrong   

"I can tell you that either a nice BFT or a big YFT is an absolute riot on a Tolman. The boat is so light it's like the old man and the sea..."
- Dave Nolan (RIP)

Online Pekka

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Re: Hello from Finland (and a question...)
« Reply #19 on: March 15, 2024, 05:13:35 AM »
I was not talking about scarfing. Just trying to make a funny remark about using "1 foot" and "12 inches" almost as synonyms within a sentence.

Thanks for confirming that 3/8 ply should bend OK!

Pekka

Nope, already wrong... if you scarf 2x 48" pieces they will be shorter than 8', by the size of your scarf.  This is a great example of the kinds of headaches that arise from trying to "improve on" or "modify" whats in the book. 

I built a Gloucester gull (bolger light dory) in Japan. I converted everything to metric (no yard sticks), but if I were to do it again, I would just keep everything imperial. Too many chances to screw things up.

1000 kg is 2200 lbs, so pretty close.

Also, I would not do less than 1/2 ply for the main bottom panels in the rear.

Offline KenB

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Re: Hello from Finland (and a question...)
« Reply #20 on: March 20, 2024, 10:25:14 AM »
Ok good!

I enjoy going to my local boat building classes on Saturday mornings, where I have become noteworthy for 2 reasons:
1) I refuse to measure anything
2) My defense of the imperial system of measurements.

This is very tongue-in-cheek (I hope there is a good Finnish translation for that term), but is perhaps interesting. My 'not measuring stuff' comes directly from my experiences building Tolman skiffs. I was asked for the Tolman "offsets"; these are the measurements of the hull at a series of stations, often taken from half models. I refused because as you will learn, everyone's Tolman is slightly different, errors cutting, faring/sanding. My deeper meaning (and the bulk of my argument with Jallii) is that the Tolman book is about a boat building technique that is very much in contrast to some of the main tenant of traditional wooden boat building. We are not building towards a specific shape based on precise measurements; we build towards utility. Build fast, go fishing.

I think I posted this somewhere else on this website, but my defense of the imperial system of measurements is that 1) the system is based on utility, not precision. Want an inch? use your thumb. A foot? check that thing at the bottom of your leg. a yard? take a stride. Yes, everyone's personal measurements are slightly off, but after about the age of 20 or so, your individual correction factor does not change. 2) The use of fractions? instead of pulling out a millimeter stick, just cut that 'thumb inch' in half! And half again! And once more. And again. You just got to millimeter precision (e.g. 1 mm ~ 1/16") without tools.  3) But fractions make math so hard! This is actually a way to make sure you are hiring guys or builders who have actually built the thing before. If you are doing any math, that means you are doing a step for the first time; if you have built it before, you did the math already, and can look up the answer. Fractions keep the clowns out.

I think the difference between inches and meters is that europeans have kings and churches and love to be told things, whereas Americans believe our opinions matter. NO KINGS! All men (and women) created equal! My favorite inches joke (again posted elsewhere on this website... sorry!): Two kinds of countries on planet earth; those that use the metric system, and one that put a man on the moon.

Ok, here is a Finnish guy using imperial measurements: https://youtu.be/xVhRm0eJ4A4?si=OL8qhbYleeyomk-1
best,
KenB

"HOW CHEAPLY CAN A TOLMAN SKIFF BE BUILT AND JUST HOW  MUCH IS SACRIFICED IF COST IS THE PRIME MOVER?"
- Bruce Armstrong   

"I can tell you that either a nice BFT or a big YFT is an absolute riot on a Tolman. The boat is so light it's like the old man and the sea..."
- Dave Nolan (RIP)

Offline jallii

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Re: Hello from Finland (and a question...)
« Reply #21 on: March 21, 2024, 10:26:26 AM »
Quote
My favorite inches joke (again posted elsewhere on this website... sorry!): Two kinds of countries on planet earth; those that use the metric system, and one that put a man on the moon.

Well before you were able to put a man on the moon, someone had to put a dog in space...
... and neither had anything to do with the imperial system. 
I can assure you that both used the international system of measurements.   
I like to find out and really understand things. A perfectionist, curious mind cannot stop learning, and picks up many things. I don't claim to be an expert. I'm not an engineer or a chemist by training. I make mistakes. If I manage to make something understandable I am happy. IF you want to build a boat make sure you follow designers instruction. Do your homework and be safe.

Offline jallii

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Re: Hello from Finland (and a question...)
« Reply #22 on: March 21, 2024, 10:52:04 AM »
Quote
My 'not measuring stuff' comes directly from my experiences building Tolman skiffs. I was asked for the Tolman "offsets"; these are the measurements of the hull at a series of stations, often taken from half models. I refused because as you will learn, everyone's Tolman is slightly different, errors cutting, faring/sanding. My deeper meaning (and the bulk of my argument with Jallii) is that the Tolman book is about a boat building technique that is very much in contrast to some of the main tenant of traditional wooden boat building. We are not building towards a specific shape based on precise measurements; we build towards utility. Build fast, go fishing.

You can try to hide being sloppy behind a desire to FASTFISH. But there is a difference with FOOD and FASTFOOD. But I would not prefer the fast choice from those two. Of course you can eat a hamburger and French fries,  when you are in a hurry, but it does not make it better than a properly prepared meal.

At some level I agree with your "deeper meaning" about what really was Renn's innovation. The book is not so much about the particulars of the defined 3 boat models, but more about the way to build one. This does not mean that the boat models are bad. On the contrary. I think they are extremely well thought of balanced utility boats that DIY builders can easily adjust to their particular needs. That said, I still think that the main thing here is just as you said. The innovation was in leaving the thin plywood on transverse frame tradition of building boats, and transferring to longitudinal framing and a bit thicker plywood.  He also cleverly hid this framing in the double use of those frames, so that you get the impression that there are no frames.  The spray rail, chine angle and keel are true frames even though he does not call them that. This is the part I agree with you, but not on the part on being sloppy.   
I like to find out and really understand things. A perfectionist, curious mind cannot stop learning, and picks up many things. I don't claim to be an expert. I'm not an engineer or a chemist by training. I make mistakes. If I manage to make something understandable I am happy. IF you want to build a boat make sure you follow designers instruction. Do your homework and be safe.

Offline KenB

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Re: Hello from Finland (and a question...)
« Reply #23 on: March 21, 2024, 03:12:07 PM »
NASA used US customary units for Apollo design and engineering, stop spreading marxist propaganda!
https://space.stackexchange.com/questions/37607/why-did-nasa-use-u-s-customary-units

Someone put that dog in space, but they killed her on reentry! It only counts if you get home safely. Aviation is still done in feet and miles, aka Freedom units.

Here's a good example of the imperial system meeting the metric system: https://youtu.be/1B-PZTqJGQo?si=T9MNvYTQx6bG-LdM
- not cgi, those are all purchasable cordless robots jumping and dancing. Watching them evolve over the past 20 years has been amazing.
best,
KenB

"HOW CHEAPLY CAN A TOLMAN SKIFF BE BUILT AND JUST HOW  MUCH IS SACRIFICED IF COST IS THE PRIME MOVER?"
- Bruce Armstrong   

"I can tell you that either a nice BFT or a big YFT is an absolute riot on a Tolman. The boat is so light it's like the old man and the sea..."
- Dave Nolan (RIP)

Online Pekka

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Re: Hello from Finland (and a question...)
« Reply #24 on: March 21, 2024, 10:25:26 PM »
Circling back to my original question: I'll let you know what I ended up doing with the floor if the project ever advances that far.

Meanwhile site admin can lock or remove this thread.

Offline KenB

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Re: Hello from Finland (and a question...)
« Reply #25 on: March 25, 2024, 09:34:37 AM »
Circling back to my original question: I'll let you know what I ended up doing with the floor if the project ever advances that far.

Meanwhile site admin can lock or remove this thread.

On the floor, I'd say:
- make sure to the bow is higher, especially if you plan to add a cabin or other heavy stuff up front.
- plywood, glass the bottoms.
- use nailers or cleats to span from side to side, so you can screw the ply ends into something. For 1/2 or 3/4 ply every 4 ft worked for me, but you can also do 2ft centers.
- to put a little crown in, glass a small support to the side of the hull that is 1/2 or so shorter than the stringers.
- some guys are using PL cement (instead of epoxy goop) to install the deck pieces to cleats, then epoxy/taping to the sides.
- Make your own deck hatches; add a little lip from scratch. Piano hinges and foam tape to seal. 
best,
KenB

"HOW CHEAPLY CAN A TOLMAN SKIFF BE BUILT AND JUST HOW  MUCH IS SACRIFICED IF COST IS THE PRIME MOVER?"
- Bruce Armstrong   

"I can tell you that either a nice BFT or a big YFT is an absolute riot on a Tolman. The boat is so light it's like the old man and the sea..."
- Dave Nolan (RIP)

Online Pekka

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Re: Hello from Finland (and a question...)
« Reply #26 on: Today at 05:38:35 AM »
Couple of pictures of the "9mm single sheet birch ply" bottom. It resisted a bit more than anticipated but got there in the end.