materials01

 

Ok.

Its probably about time we have a good look at boat construction.

Im not going to talk about kevlar, carbon and moulded fibreglass.

Its not that easy to work in and we are looking at a first-ish, from scratch boat build project. That lots a fair bit more advanced.

Three main methods are readily suitable:-

Cloth over a frame, waterproofed - canvas.

Stitch and glue.

Lapstrake, or clinker.

Weird things trees.

A tree makes bark during the spring, summer, and shifts water and nutrients up and what if gets from sunlight down.

No Idea how. No Idea why.

In the winter, the inner layer of the bark, which carried the sticky resin, seems to solidify somehow, and the resin stops flowing.

Thats the bit that becomes wood over the winder.

The outer bit of bark thickens in the next spring and it all starts again.

Its the wood that interests us.

It seems to be made out of long bits of fibre, a bit like lengths of nylon wool that it binds together with resin/glue.

Somehow, the whole lot flexes quite a bit before it gives up and fractures into splinters under compression - being squashed, tension, being stretched, or being bent. - forgotten the term for it. Getting senile.

The resin glue that holds the wood together is also heat sensitive. If we heat it, we can get it to allow the fibres to move.

You might have seen Ray Mears straightening green sticks over a fire to make arrows. We can use this technique to make some boat bits in two of the methods we are interested in.

Ie.

Cloth on frame, and lapstrake.

Understanding these things about wood makes using it easier.

So....

Hopefully, you have managed to er... collect a few tea stirrers, so that you can have a go.

As the tea stirrers come from the cafe, and we need hot liquid...



Hot liquid is enough on strips this thin....



By the way...

The tea is hot and will burn you if you let it.



Leave it to soak, while you drink the tea....

Or if that sounds disgusting.....

Dont drink the tea...



After its been soaked in hot water, or tea, the glue that holds the fibres in the wood together softens and allows the fibres to move.

This strip is still whole but is curled up in the milk pot.



I bent these two together, side by side until one snapped.

The broken one wasnt cooked, the bent one was.

I had the end of a baton in my pocket, with some elastic bands.

I used them to keep some stirrers bent while they cooled and set.

Ive left it for a week so the sticks can dry out and the resin set in its new place....



The wife was lurking, so shes going to do some of the complicated testing later....



Ok....

Elastic band over the end of a curved bit....



Two straight bits held against it...



Wind the band round the four corners of the joint, then stretch the end loop over the end of the curved bit...



Slide the joint around the curve until its in the middle of it, Ow! Being careful not to snap the band and having to start again. Grrr....




Put a second pair of straight stirrers on...



...and a third...



Wind another band around the end of two fingers....



Push the three straight sticks of one end into the band....

Slide the band off your fingers and onto the sticks...



Do the other end to match...



Have a look at the shape and decide if the middle curve is too long.

Ive pushed this side down until the two straight sticks are sitting in line, instead of slightly crossed...





I need to push this side down too....



Both pushed down so the shape is more er....canoey...



Ive snapped off the two protruding ends from the curve...



That canoe frame is now complete.

Have a go. Make your own one.

Dont worry if its not that neat. Its only got to stay together long enough to be floated.

Anyhow, if it falls apart, you simply make another one out of the bits or start again.

We will cover it and launch it later.

And now for something completely er....similar, but not quite the same....

Overlap two sticks and put a band between them....



Wind the band around the sticks, then pull the end loop over one of the short ends of the sticks.

Make three....



Wind a band round both ends of two of them.

Try laying them between two fixed points (cups probably arnt the best thing to use as they might tip over).

Feel how much they bend if you push down on them - as demonstrated by my assistant....



Snap both ends off another stirrer and wedge it between the sticks and test its resistance to bending again....



Lol!

It wasnt me that tipped up the cup!

Luckily it was the empty one.

Try this test again with the completed frame...



Results...

The sticks without a crosspiece, or thwart, bend a lot more than the one with it.

The curved thwart bends more than the straight one.

Conclusion....

Making big triangles using your thwarts and gunnels makes it stronger.

If its stronger, you can make it as strong with less wood - which means less weight.

Stick another piece onto the thwart and add the bottom runner to complete the second frame....



We are looking to see if the various theories work with these models, so it doesnt really matter if they arnt lovely, only that they work.

It will not even matter if they arnt symmetrical.

Ok...

Having made the frames, its time to skin them.

I know it may sound silly, but you dont actually need to have a properly waterproof material for this, so long as you coat it sufficiently.

So.....

A sheet of printer paper.



Im not cutting it to make it fit, Im simply crunching it into roughly the right shape.

Im not too worried about making it particularly streamlined...



Its er....sort of boat shaped lol.






For a waterproofing membrane I er.....

Looked in the fridge...


Now to carefully coat it on all outer exposed faces...



Or in other words simply smear it with butter, margarine, lard...something oily and basically water repellent that wont destroy the paper.

There...Done with all the attention to detail and skill of the average 4 year old.



It simply works.




The lack of freeboard would be a problem if there were any chop, but its surprisingly stable and tracks pretty much straight.

Ive loaded it with coins...



As you try and tip it, by leaning on the end of the curved stirrer, it resists and then shoots back up as you let it go.



This is actually, not a bad little boat. The paper is just stiff enough to keep its shape.



Hopefully, when you build yours to play with, you wont be quite so rough lol.

The inside of the paper is being kept dry by the margarine.



My clock goes backwards. Its just gone 9.30. The paper boat has been floating for about 5 minutes already.



Heres another curved stirrer boat covered with clingfilm....



Its not got enough weight in it to make it float level...



..so I piled more on.

and some more...

and even more.

Astonished at just how much weight it took.



Finally, it sank....



Thats how many coins it took...



The paper skin is still holding up fine...



Ive just wrapped the straight stirrer boat in clingfilm...



Thats the spreader thwart thing back in....



It wouldnt float without coins to keep it level as its triangular shaped across its mid section.



It didnt take as many to sink it either.

Nor was it anything like as stable as the other two...

Took the thwart apart and assembled it the other way round to make the boat wider and shallower...



It still want anything like as stable or capable of carrying weight as the curved stirrer boats...



10.15 ish....



The paper boat is still floating fine and not taking on water...



Conclusion....

The paper boat had a better shape due to the curved stirrer and the stronger paper.

It sat in the water better and would be my choice out of these 3.



With the cling film actually pulled tight, it may have been a different story.

It may be due to my lack of skill with cling film.

I think its due to the inferior shape caused by the cling film going concave.

However, its pretty obvious that these methods of boat building are clearly viable and simple.

Still...

As always, dont take my word for it, try it for yourself.

Simply reading about it will give you a level of understanding.

Actually building these models will take that theoretical understanding and massively increase it and change it into practical understanding, which is infinitely more valuable.

Again....

Dont take my word for it, try it yourself.