Gaps or no gaps between the seams?

[gbinga]

It all comes back to what kind of boat you want and how you want to use it. If you can get it on and off the truck and in and out of the water without hassle, it is light enough.

I don't think there is any advantage to making the boat lighter except the need to make it easier to launch. I wanted my pirogue easy to handle, and it came in under sixty pounds and satisfied me completely. Another guy in a different situation might need it lighter, and there are ways to accomplish that if you need to. Still another fellow might want his boat to be a real abuse taker and put up with the extra weight so as to gain durability.

I imagine you could build out of half-inch ply if you needed the boat to be super tough. Sucker would be heavy, but I bet it would paddle just fine. Great thing about wood boats, as Chuck and others have repeatedly pointed out, is that you can have what YOU want, for a reasonable price. You ain't gonna accomplish both of those goals without building it yourself.

George

 

[JEM]

I used my estimating spreadsheet (which has historically done a good job at estimating weight) and a panel 1/4" thick with 6-ounce e-glass on both sides will weigh about 4%-5% less as a panel 3/8" thick just epoxy coated. That's assuming same species of ply.

However, figure on a little extra additional weight because you have to bond the 3/8" panel to the side of the boat with additional glass (assuming that's what you'll use). If you were using 1/4" and fiberglass, you could cover the panel and bond to the sides with the same piece of fiberglass.

Another advantage of glass both side is protecting the plywood better long term and preventing any checking or surface cracks.

The 1/4" with glass should be strong enough but it's hard to say for sure without knowing more specifics about the design. Best thing to do is consult the original designer.

3/8" might be quicker to work with.

Is using 3/8" a bad choice? No. Just depends on what you want to achieve.

 

[Kayak Jack]

Beekeeper, you have a good point there. I use a boat as a tool, not as a decoration. I understand what you mean. Real world situation always trumps imaginary ones.

 

[gbinga]

... ut is it stronger than a well attached inside chine? I don't know as I've never seen destructive testing for comparison. I know from my experience that it doesn't NEED to be stronger than the inside chine..../

Seedtick,

Has your experience included building boats with 1/4" plywood? Most of the boats of yours I've seen are solid lumber and heavy; I'm wondering how often you've used light plywood and inside chines?

I'm not arguing with you - just looking for info. I built my pirouge with 1/4" ply, inside chines, 'glass and epoxy on outside only. I like the way it turned out, but can't say that I've used it enough to know if I will like the durability.

George

 

[Kayak Jack]

George, regardless of Seedtick's answer (which will be informative for sure) you should consider glassing the inside of the bottom. Reason is, when, not if, you get hung up on a root/rock/obstacle that bends your boat's floor upwards and inwards, the glass will protect against cracking, crazing, and splintering on the inside.

 

[seedtick]

the pirogue that Jack used on the first great pirogue expedition to lake verrett was one of ours from 1/4" sides and 3/8" bottom inside chine- no glass, no ribs

haven't weighed it but it probably weighs 60 lb

I have my dad's 1953 vintage 14' bateau - 1/4 " marine ply inside chine weldwood glue - no epoxy , no glass it's still as solid as the day it was built

we build 2 or 3 plywood boats a year BUT we use marine plywood and not the big box cheap stuff - marine plywood is stronger than the $10/sheet stuff

 

[beekeeper]

Seems each time I explain my question I haven't. I will try to eliminate some of the variables injected here because I did not explain enough, maybe?, what ever?, I don't know. :? Some points will have to be discussed by others more knowledgeable than me.

JEM
Thank you so much for your estimate. Your spread sheet should be accurate enough for my needs. Would you know how much a sheet of 3/8" a/c might weigh? I could then estimate the savings of any size boat. I probably would not need extra glass for 3/8" because I wood use chine construction. I"m more comfortable with it. Please nobody get ruffled. I'm not saying it's better.
You stated "Is using 3/8" a bad choice? No. Just depends on what you want to achieve." Trying to narrow the question, I need a boat that is put it in the bed of truck easily light weight, built with chines (my preference, but could be optional), and won't break apart in the real world (at least in my world) of non manicured launch sites, and paddled in stump and logged filed creeks and lakes. My world also includes these facts; I weigh 300lbs. and not as agile as I once was. This don't mean I'm dead or inactive. I did and will chose a wider model in what ever type boat I build "next" (2ed. time I've used that word (hope Mrs. beekeeper doesn't see this ).
"Inside" chines has been referenced here . Is there a difference in strength between inside and out side chines? If anybody has ran comparative stress tests, can I find results in the Journal of Boat Science.



beekeeper

 

[oldsparkey]

No Boat Science here , I have paddled with guys heavier then you and in the 6-5 bracket....... They used a Pirogue made from 1/4 in Luann and was glassed all the way around. Some even entered races with them on our rivers.

It all boils down to one simple thing....... It is your boat , make it the way you want it and if you are not happy with it then give it to a friend ( Or someone you do not like if it is really bad ) and build another the way you think you want it. The What If's or Why's and How's can consume all that time you could of been using to made it and be out using it.
No matter what anyone suggests on here without getting into your brain and understand your thoughts can't make a logical suggestion about what you want. Only one person knows what you are after and that is you....

Start the build and then ask so we know or have a small idea of what you are trying for , then some suggestions can be focused in on the discussion. Till then everyone is just guessing and that is not the greatest thing to have.

If you want it out of 3/8 inch lumber then go for it , especially if you feel safer with it. Want it all wood and painted , no problem except someone might suggest to glass in the seams and epoxy saturating the wood before painting it like i will or would tell you if you asked. :wink:

JEZEeeeeeeee you have built one great boat and by doing that you have to have an idea in your mind about what you want and any improvements to it ....RIGHT.

OK... Tell me to shut up and go over to the corner and sit there for two days.... Dam , I like that corner , it and I are good friends. :lol:

Chuck.
PS. I apologize for not using the large print but I figured you can read the normal size one , like the rest , well almost most all of the rest of us. :roll:

 

[JEM]

Would you know how much a sheet of 3/8" a/c might weigh?

what species?

I don't think anyone will badger you for building your boat your way. If anyone would get needled for not following instructions, it would be this forum's founder. :mrgreen:

 

[gbinga]

...we build 2 or 3 plywood boats a year BUT we use marine plywood and not the big box cheap stuff - marine plywood is stronger than the $10/sheet stuff

Agreed.

Do you use marine fir, or tropical stuff?

If you DO use marine fir, are you glassing inside and out to keep it from checking and cracking as it weathers?

(I'm interested in the traditional building techniques, but I gotta stay with plywood 'cause there is NO WAY I'm gonna inflict my carpentry "skills" on the kind of lumber you guys use)

George

 

[Kayak Jack]

... but I gotta stay with plywood 'cause there is NO WAY I'm gonna inflict my carpentry "skills" on the kind of lumber you guys use)

George, you're at where I'm at. I can wood butcher a good grade of plywood and end up with a very nice boat - strong even if a bit ugly. I love the cypress sinker wood; it's beautiful. But, I can neither be skilled at developing it, nor afford the weight.

 

[Oyster]

... but I gotta stay with plywood 'cause there is NO WAY I'm gonna inflict my carpentry "skills" on the kind of lumber you guys use)

George, you're at where I'm at. I can wood butcher a good grade of plywood and end up with a very nice boat - strong even if a bit ugly. I love the cypress sinker wood; it's beautiful. But, I can neither be skilled at developing it, nor afford the weight.

I sat BS! Just kidding,, First off go by you some shelving boards which is normally white pine and reasonable, picking through them and practice building a hull using pictorials thats already on here even from Seatick. There are other examples too. Always work your way up. Education does come with a bit of costs. When you do this, don't mess with glues until you get all things bent and together, just dry fit the parts and use fasteners to connect the dots. Then if you don't like it, you can adjust and go forth.

 

[Steve]

I toyed with the idea of planing down some of that #2 knotty pine they use for shelving to 1/4" thickness and using it to make a pirouge. . . I have about a dozen or so 18 footers in 1"x12" with some solid knots and lots of birdseye in Texas. . .
Hopefully, that #1 son won't do something foolish and use it before I can get down there to get it and bring it back. . .

George. . .don't do like me and wish ya had. . .Thinking all those knots and that birdseye would make a good lookin' boat. . .
I should've and damned well wish I had

 

[seedtick]

gbinga,

we use fir marine plywood, mainly because it's more available around here than okume or meranti - i think the last 1/4" we bought was about $50/sheet but i hear the price has gone down since our new president has been saving the economy

we put whatever finish the customer wants - typically we would put a coat of epoxy on the bare wood and then paint it

It seems to be the nature of painted fir plywood to check - my dad's 1953 bateau that i talked about in an earlier post has been checked ever since i can remember - but it doesn't cause it to leak or take up an appreciable amount of water when we use it (at least not enough that i can tell if it takes up any). The checking as far as i can tell is confined to the veneer layer. I always figured it to be like the stress cracking in the gel coat of a glass boat - more cosmetic than structural.

we don't use glass because we feel the boats are strong enough as is - glass/epoxy isn't a cure all - if water gets in under the glass epoxy coating it tends to stay there. Talk to folks that have old fiberglass boats with wooden stringers and transom encapsulated. They tend to accumulate water and rot. Water gets in as a liquid but has to get out eventually as a vapor. A given volume of water occupies something like 600 times that volume as a vapor. So once in, it's a long time coming out.

The other thing about epoxy is chemical sensitivity. I spent all of my career working with various chemicals and chemical sensitivity is nothing to scoff at. It can occur after many contacts or just a few - kind of like folks sensitivity to poison ivy. If I remember correctly something like 10% of the people that come in contact with epoxy will develop an allergic reaction. Most of that is a skin reaction -dermatitus. 20% of the 10% will develop an inhalation allergy -which is not good at all. Imagine having poison ivy in your lungs - pulmonary edema and stuff like that. Not trying to scare anybody but know that epoxy is not exactly mother's milk. Keep it off your body, don't work with it in confined spaces and it's best if you wear an organic respirator

 

[Kayak Jack]

I sat BS! Just kidding,, First off go by you some shelving boards which is normally white pine and reasonable, picking through them and practice building a hull using pictorials thats already on here even from Seatick. There are other examples too. Always work your way up. Education does come with a bit of costs. When you do this, don't mess with glues until you get all things bent and together, just dry fit the parts and use fasteners to connect the dots. Then if you don't like it, you can adjust and go forth.

Oyster, usually, I can follow your thoughts. You got me beat this time. What are you trying to say to me here? Thanks.

 

[Oyster]

I sat BS! Just kidding,, First off go by you some shelving boards which is normally white pine and reasonable, picking through them and practice building a hull using pictorials thats already on here even from Seatick. There are other examples too. Always work your way up. Education does come with a bit of costs. When you do this, don't mess with glues until you get all things bent and together, just dry fit the parts and use fasteners to connect the dots. Then if you don't like it, you can adjust and go forth.

Oyster, usually, I can follow your thoughts. You got me beat this time. What are you trying to say to me here? Thanks.

Hum, I thought I was clear in replying to your initial issue of not having the skills to work with good wood, especially sinker cypress. You said you wold butcher the good stuff. So I suggested to go by the white pine type boards or shelving boards which normally comes in 11 1/2 widths and practice building a pirogue just like the ones Seetick has posted on some of the other threads. Those would make a great tutorial to follow.

By the way, FWIW, I have slepted at a Holiday Express but don't do mind altering beverages if you are wondering. :wink: I think my mind and fingers and eyes don't always work in unison late in the evening though if there is some confusion in my print. :cry:

 

[beekeeper]

JEM
ON my build I used common building ply B.C. (pine I believe). Not pretty, but that's what I found locally and in my budget for first build. Also the reason for the paint job. Any species suitable for boat building would work for figuring the difference in weight asked in my question, as long as my comparisons remained constant in the equation.
Hang on! These are my thoughts (example); If the3/8" bottom weighs 50lbs. and the 1/4" bottom with glass weighs 5% less that would be a savings of 2.5 lbs.(sure hope my math is correct). That may not warrant doing the extra work. I am conceding all other factors are equal or are acceptable to me. These (strength, durability, longevity) have been argued (discussed) already.

Chuck
I would be the last person to say go to the corner. I have tried to express what my goals for the boat are. There is no perfect boat. I like the one I built, but trying to improve the qualities that don't suit me. I can admit mine is not perfect (for me), and try to not make the same mistakes. All part of the learning experience. I'm trying to become more knowledgeable so I can make better choices. The print is fine. I just got new glasses.

beekeeper

 

[JEM]

If I remember correctly something like 10% of the people that come in contact with epoxy will develop an allergic reaction. Most of that is a skin reaction -dermatitus. 20% of the 10% will develop an inhalation allergy -which is not good at all.

I hadn't heard that one. Did your source for this information provide any hard data? Or is it anecdotal information based on his/her experiences?

I've experienced some reaction when using very cheap quality epoxy hardener. Like the 5:1 mix ratio stuff.

 

[Oyster]

I am not sure of what may be known as hard numbers. But I can attest to the folks along the banks becoming sensitive to the point that some can even walk in a shed with airborne dust or dust residue in them. As you mentioned, the five to one is worse for me. But even with the slow set, I am still required to space my use of epoxy to small sections now. Even when I only do glued laps with nothing but mixing and applying in an area thats closed and will require no sanding, my eye lids swell up and I continue to have to coat them with Hydrocordozone creams. Of course even with long sleves, my wrists look like poison ivy has hit them. Thank heavens I don't have to do it full time anymore and found numeous alternative builds for my pleasure also using flex caulks for the projects of fun.

 

[seedtick]

here's something i found from West Systems - it pretty much tracks what i remember, of course my remembering ain't what it used to be
the bottom line is the same, this stuff isn't mother's milk

http://www.westsystem.com/ss/health-eff ... -to-epoxy/

had a guy working around me in the late 80's that got sensitized to toluene di-isocyanate - the reactive component of polyeurethane. He couldn't get within 50 feet of the stuff. Finally had to transfer him to another job