Plywood and Such, Complications, etc.

[mgriffin]

In the process of building my small boat, I will need to now something about plywood. I now some things about it, but my main question is about fiberglassing it. Do I have to? What I'm trying to say is how did the Vikings make a wooden boat that didn't sink or get waterlogged without fiberglass? Fiberglass was invented hundreds, if not thousands of years after they built their boats. Did they seal their boat with tar? I've heard of people using cotton and tar to make a caulking mixture to seal the seams, but how did they keep the wood not covered from getting waterlogged? Or did they smear the all the hull with tar?

[hoytedow]

The Vikings did not build boats with plywood.
Many kinds of fiber can be used to rope a seam, including that made of cotton, sisal, hemp, oakum or even human hair if need be.
The wood boat, as it gets waterlogged actually swells as it takes up water and if the joints are well made, the swelling actually seals the hull against leaking.
The tar referred to in much ancient boatbuilding accounts is actually pine tar, and not, for the most part, tar derived from petroleum based chemicals.

[PAR]

They didn't seal their boats, which in fact leaked like a bottomless bucket. These boats had members of the crew constantly bailing or working primitive pumps. Wood did get water logged and they did smear tar all over everything, including the hulls. Of course the tar also got all over everything else, people especially. It was tracked all over the boat, into food, literally everywhere.

Christopher Columbus' ship's logs aboard the fleet showed they "manned the pumps" about 15 minutes every hour during the first Atlantic crossing, meaning things hadn't gotten much better in spite of 500 years of maritime advancement.

So, your thoughts of going back to a "kinder and gentler" time when boat building was easier, cheaper and preformed with hand tools is novel enough, but not particularly practical.

Unfortunately, there's no sitting around the camp fire, eating smores and singing Kum Ba Ya, if you go back to these methods.

Plywood has much to recommend it and some draw backs, just like every other choice in yacht design and construction. There's no way around this, it's just a reality of life.

No, you don't have to 'glass plywood, but it's recommended by everyone for good reason. If you elect to not 'glass you plywood, you can expect certain things to happen, that may not if it is 'glassed. Again, this is one of the trade offs that must be accepted.

[tkk]

Originally Posted by PAR

They didn't seal their boats, which in fact leaked like a bottomless bucket. These boats had members of the crew constantly bailing or working primitive pumps. Wood did get water logged and they did smear tar all over everything, including the hulls. Of course the tar also got all over everything else, people especially. It was tracked all over the boat, into food, literally everywhere.

PAR, it doesn´t need to be like that! Pine tar used in a proper way is not as sticky as you might think. At least not up here in Scandinavia.

My old Dad said that the tar has to be applied before the ice melts in Spring. That way it has enough time to dry and settle and it won´t be sticky even on the sunniest days (by Finnish standards ) of the Summer. I think the sunshine combined with cold air also helps the tar set.

If applied too late the tar will be sticky the whole Summer and you will have it in your hands, clothes and everywhere.

Since you don´t have ice in Florida to time your tar application, I don´t know if it works at all down there

[Manie B]

Sorry a bit off topic

Christopher Columbus' ship's logs aboard the fleet showed they "manned the pumps" about 15 minutes every hour

this is a well known fact

but

have you guys got any details or drawings of how those pumps were made in those days, i have not come up with anything meaningfull, would be nice if someone that knows the history could come up with a drawing or good description

thanks gents

[hoytedow]

I believe they were double piston double action pumps manned by 2 sailors at a time. I will try to find a picture.

[hoytedow]

I couldn't find any illustrations, but they were described as made of copper, with lead sheathing, having leather flapper valves...

[apex1]

Quite often these pumps were simply made of wood. The principle arrangement is shown here:

Regards
Richard

[hoytedow]

Thanks, Richard. That was the configuration I had in mind, except with a T-handle on each end of the lever.

[apex1]

There is a handle to be attached on purpose, but for ease of lines handling removed in everyday service.

[hoytedow]

Thanks for the info. I saw the holes in the lever and suspected something was missing.

[missinginaction]

Unfortunately, there's no sitting around the camp fire, eating smores and singing Kum Ba Ya, if you go back to these methods.

PAR, I had to pick myself off the floor from laughing! You should go into show business.

The guy was asking about not glassing plywood though. One of my old friends down at the club uses cotton and this homemade mixture of some kind of marine paint some kind of oil (linseed?) and the wax from the rings that you use to seal toilets to the standpipe. We work this mix into the seams of his wooden hull. It's a lot of work, but this guy is almost 90 and he's an old Navy lifer. He knows his stuff and his homemade mixture performs very well and costs next to nothing. BTW his boat was built in 1913 and she's a beauty for her age. I've learned a lot from this guy.

I'd say to always glass plywood. Am I right?

Now I'm gonna go light me a campfire....anybody know the lyrics.........some one's calking lord, Kum By Ya.....

MIA

[mgriffin]

Yeah, I figured that you had to glass the entire hull of the boat. I don't want my boat to be cheap, and I might end up spending 200$ to build it, or if I really want a boat that lasts, I could spend 300$ on it. I'd probably have to use 100$ for the glass alone though! I want a boat that will take a beating and shake it off and keep going. Hell, I might make the hull out of 1/2 inch ply if possible! I just want a boat that will outlast those cheap plywood so called boats made out 1/8 inch ply and are as fragile as an eggshell. I might take it on the Platte river if we move to Colorado, so I would attach a metal strip to the bottom so it can take a grinding without any major damage. I am also going to put six 10" bumper tires on it so I can hit stuff and survive it. To strengthen the hull I will also add a frame out of 2x4 running from bow to stern and from port to starboard. I will use that as a seat, or at least a 1' by 3.5' board on top of the frame running from port to starboard. Don't remind me how heavy it's going to be! We have a truck, we could just put it in the bed of it and tie it to the truck to keep it from slipping out. I can lift 70 lbs, maybe a bit more, but I still might need some help getting it in the bed of the truck. I would estimate the weight to increase by 20-25 lbs from the original 40 lbs. You can tell me how much it will weigh with these mods if you like, but remember it has a 9" draft with 350 lbs of displacement. So that is 40 pounds for every inch of displacement, or 38.88 pounds if you want to be accurate.

[lewisboats]

1/8" to 1/2"...quite the jump. You built like Arnie? Any boat that someone would make out of 1/8" ply is done for light weight and portability...but simply going to 1/4 would MORE than double the durability of the boat at a penalty of only doubling the weight. Your average fir ply will run about 25 lbs per sheet of 1/4"...figure your weights from there. The African mahoganies will run 18-22 lbs/sheet of 1/4".

[PAR]

Timo, having first hand experience with real tar and the stuff going around as "tar" both are problematic, though I suspect you're correct that your climate may be better suited for this material. I know I've read about fine, 19th century ladies, dressed in their best white outfit, for their first ship board excursions, just to find they're covered in black in a few hours and miserable.

I have seen some sketches of 500 year old bilge pumps and they were double piston pumps as mentioned, with leather valves. I would imagine there were several different designs, though the simplest and most reliable was likely most common. Maybe bucket chains or augers were tried too. It difficult to tell what was employed with the minimal amount of documented information we have from these eras.

Steve, Michael is a lad of 15 and though seemly bright as 15 year olds go, "not ready for prime time" if you're old enough to know what I mean. He'll figure things out soon enough.