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dtsman
03-03-2012, 08:03 PM
Hey guys,

Do more reading than posting. I am building a cedar strip boat. I am planing the stips down to a 1/4" thick and 3" wide. The boat is 16' long and 5.5' wide. It has 4 ribs and the transom. Today I put the last side board on and getting ready to do the bottom when out of nowhere I heard 3 loud pops about 15 minutes apart. 2 of my strips that are in the middle and have been glued in place for over a week, split. in multiple locations. The strips are glued to the ribs and to each other. The side that spit had clamps on it when it split. Pretty spring day in southeast TX, low temp in the 60's and low humdity.

Any ideas why this happened?
Will the fiberglass and epoxy prevent this from happening when I am on the water?
And it doesn't appear the clamps will pull the splits back together.
I am trying to insert pics. If they do not show then there are links to them as well.


http://i39.tinypic.com/2hgbazk.jpg

http://i39.tinypic.com/2hgbazk.jpg

http://i44.tinypic.com/swwlt0.jpg

http://tinypic.com/r/swwlt0/5

http://tinypic.com/r/2hgbazk/5

Thanks,
Bo

Ron Williamson
03-03-2012, 08:55 PM
Wood shrinks measureably across the grain(the planks).
It doesn't really shrink along it's length(the frames)
When you glued the plank to the frames you tried to stop the shrinkage.
I'm guessing that your cedar was too wet.
R

LSC
03-04-2012, 07:56 AM
The strip construction on canoes & kayaks, for example, uses much narrower strips -- the 1/4 thickness is typical (for canoes) but the 3" width might be allowing for too much expansion, as Ron pointed out. Are you painting this boat or do you intend to finish it bright? If the former, you might fill in the cracks with a mix of epoxy and microballoons, then get the glass cloth onto it, on both sides, as soon as possible. This should slow down/prevent any swelling of the grain.

Also, in conventional strip construction (again, canoes and kayaks) the boats are typically frameless.

FYI -- some traditional canoes (cedar ribs and wide, thin planking), typically canvas covered, have been successfully fiberglassed, but the wide planking is usually extremely clear and 1/4 sawn. Hope this helps.

Bob Smalser
03-04-2012, 10:35 AM
Interesting problem. I have some questions.

Exactly how wet is your wood? Some of it looks like it was planed while green. Are these cedar fence boards?

While there is nothing wrong with flatsawn with wild grain and lotsa knots per se, to plane it down to a quarter inch is a bit extreme, given the stresses inherent in such boards.

Sure you didn't buckle your panel with the bar clamps? Look at the varying heights of the bar above the wood and the deflection of the bars. Unless it's a distortion caused by the camera, it appears to be uneven clamping pressure and lots of it, to boot. Probably too much for epoxy, too.

http://pic20.picturetrail.com/VOL12/1104763/2595357/401392657.jpg

I also don't see any evidence of glue in a rough assembly that would normally have squeezout. Did you use enough to be effective?

The good news is that all this damage can be buttered up and covered with glass. Providing the wood is sufficiently dry to take glue, that is.

James McMullen
03-04-2012, 11:24 AM
Those "strips" are enormously wider than is standard for strip planking. I think you built stresses right into it. And you tried to rigidly glue those wide edge-glued side panels straight to those cross-grained ribs? That's bad practice in any variety of woodworking. Also, how are you planning to skin the inside with those ribs in the way? 1/4 strip planking requires a skin of FG on both sides. That's the entire structure of the boat! The cedar strips are a core material to gain girder cross-section for the inside and outside FG layers. Standard cedarstrip construction uses temporary station molds to assemble the boat, so that after the outside is glassed the boat can be flipped over and have the inside done before any bulkheads or framing or structure is built in. Did you not have any plans to follow?

I'm sorry Bo, but you might want to stop hurling blood, sweat and money into this thing and reassess some things before you go any further. I see a lot of poor practices, and I'm not crazy about he hull shape either. Did you design this yourself? I don't mean to be brutal, but you might spend a lot more money and time trying to rescue this experiment than it would take to start over and build to a proven plan using established techniques. I think you are headed for failure with this one, and this warning call might be the best thing that could have happened for you.

Peerie Maa
03-04-2012, 11:42 AM
Those "strips" are enormously wider than is standard for strip planking. I think you built stresses right into it. And you tried to rigidly glue those wide edge-glued side panels straight to those cross-grained ribs? That's bad practice in any variety of woodworking. Also, how are you planning to skin the inside with those ribs in the way? 1/4 strip planking requires a skin of FG on both sides. That's the entire structure of the boat! The cedar strips are a core material to gain girder cross-section for the inside and outside FG layers. Standard cedarstrip construction uses temporary station molds to assemble the boat, so that after the outside is glassed the boat can be flipped over and have the inside done before any bulkheads or framing or structure is built in. Did you not have any plans to follow?



I'd run the internal Fg in vertical strips between the frames, lapping onto the frame faces. Not perfect but should be adequate. At least everything is straight lines. It needs floors to tie the bottom frames together across the keel as well.

David G
03-04-2012, 11:56 AM
I guess my first question is the same as James. What designer, what design, and did they really tell you to configure it this way?

thedutchtouch
03-04-2012, 11:57 AM
i would not waste the fiberglass on that hull, believe me, i thought it was an awesome idea cutting corners for my first boat, it lasted all of 1/2 a season (to be fair, neglect during the winter and damage during a hurricane is what did it in, but it was on it's way out regardless. what James said may seem harsh but he's just trying to be helpful and make sure you end up with the best boat possible.

dtsman
03-04-2012, 12:03 PM
Thanks guys. I figured it had something to do with shrinkage.
I was just mostly concerned with can this happen again after glassing?

I have watched 100’s of videos on line on you tube, etc. and reading this forum before I dove into this. I was going to do a canoe, but decided to do a full boat.

I have copied the hull shape from other boats I have looked at. It is a 10 degree vhull. The bow is 10 degree as well. I put ribs on the inside for 2 reasons. 1. So they can be blocked together and transfer the outboard torque throughout the whole boat and not all the torque at the transom connection. 2nd, so I can lay a flat floor in it.

The sides are not bowed from over clamping. I cleaned the glue drippings as I clamped each board with a damp cloth.

It is just cheap cedar fence pickets with knots. I felt the knots would give it character. If it is ugly after glassing then I will paint it.

This is a video with what I was going for on the interior and the finish. You can see it in the first 5 seconds.
http://www.youtube.com/watch?v=O_KR4Uv9NM0&feature=related (http://www.youtube.com/watch?v=O_KR4Uv9NM0&feature=related)

Peerie Maa
03-04-2012, 12:09 PM
Thanks guys. I figured it had something to do with shrinkage.
I was just mostly concerned with can this happen again after glassing?


It may rip the glass (called unzipping) if the glass is not thick enough. You need inputs from other forumites who build in this style.

David G
03-04-2012, 12:25 PM
It may rip the glass (called unzipping) if the glass is not thick enough. You need inputs from other forumites who build in this style.

I don't think there's anyone else who builds in this style. In designing his own boat, the OP has created a strange, hybrid, style that has some issues.

I see two options - 1. pronounce this a failure, and buy a set of proven plans with which to start over. 2. go ahead and finish it off, knowing that it's an experiments, and likely a short-lived one.

If #2 is chosen - I'd finish planking it, let it dry (crack), fill the splits and cracks with thickened epoxy, and glass the exterior with 6 oz. glass. Then I'd glass between the ribs on the interior with 6 oz. or heavier glass... and hope for the best.

I'd choose #1. It's plenty enough to learn the details of a proven system without trying to invent your own system. That comes later - much later - after you've got many boats under your belt... if at all. I think you have over-reached, and - through a surfeit of ignorance - have failed. I'd admit it and start over, no matter how painful that is. It'll be safer for you and your family/friends.

Robert W. Long
03-04-2012, 12:30 PM
Is the Schoonersrus guy back?

Peerie Maa
03-04-2012, 12:58 PM
Is the Schoonersrus guy back?
No, there is a real picture of a real build. Futher on than Afroman as well.

thedutchtouch
03-04-2012, 02:57 PM
1. having the ribs or not is not the issue, it's the order of construction. most would say to build on temporary molds, glass the outside, flip the boat, remove molds and glass the inside, THEN add the ribs, that way the ribs don't "break up" the inner fiberglass layer, which somewhat compromises it's strength.

2. those knots, particularly at 1/4 inch thicknesses are going to be huge weak spots in this type of construction the wood is a core and the fiberglass provides most of the structure, but i would still be wary including that many and that size of knots. if you want to use the same material, i'd cut around them and scarf shorter pieces together (at least a 8:1 ratio for the scarf meaning if the board is an inch thick the scarf should be 8 inches).

James McMullen
03-04-2012, 05:27 PM
You could finish planking, glass the outside, then chop out and grind off all of the framing and do the inside skin. Then when the structure is complete, add your frames, floors and sole.

If it's a powerboat then you're probably looking at a minimum of a couple of layers of 6 oz inside and out, maybe 10 oz to be on the safe side, with three layers biaxial tape over a fillet on the inside chine, plus at least one layer of biaxial for the outside chine. I'd also add an additional layer of 10 oz on the outside bottom for abrasion protection if you're going to be beaching her regularly. Yep, with resin and glass you're probably at least a thousand dollars away in materials before you even come close to a safe and useful boat. Are you sure you're on the right track before you cast those pearls?

Tim Marchetti
03-04-2012, 05:40 PM
Nothing about this build looks right. I truly fear for your safety. Even if the materials used were not junk, 1/4" strips and and 6oz. glass are too little for a 16'x5.5' power boat.

dtsman
03-04-2012, 06:27 PM
The skeleton (ribs and keel and the way I tie them all together) is where I had planned all the strenth for the outboard's torque. I possibly could add a 1/4" thick marine plywood to the interior.
With 6oz fiber on both sides, are yall saying my boards can break in-between the ribs from the water hitting it.

In theory, if I put a large 16' ski on the bottom of the keel, the boat would ski across the water without any cedar strips and only the framing skeleton would be stiff enough to handle everything. (My carpenter's mentality)

So, knowing that the framing was the core design for strength. Feedback on the adding plywood on the backside or other suggestions.

James McMullen
03-04-2012, 06:43 PM
The skeleton (ribs and keel and the way I tie them all together) is where I had planned all the strenth for the outboard's torque.

Seriously? With this as your structure?

http://i44.tinypic.com/swwlt0.jpg

Bo, stop. Just stop. You are not qualified to design a powerboat yet. You need more boatbuilding experience first. You are headed straight for a cliff, amigo.

Gib Etheridge
03-04-2012, 07:45 PM
"Bo, stop. Just stop. You are not qualified to design a powerboat yet. You need more boatbuilding experience first. You are headed straight for a cliff, amigo."


There are lots of people here who are well qualified to advise you. You should listen. If you do maybe someday you will still be around to advise the next crop. If you don't somebody is going to get hurt.

JimConlin
03-04-2012, 09:19 PM
I'm glad I came late to this thread, 'cuz it's all been said.
It could be excellent kindling.

Bob Smalser
03-04-2012, 10:21 PM
Now that you and your boat have been thoroughly dissed, don't hesitate to PM me to discuss how to make something useful of it.

It will never be a stripper as convention defines them, and it'll never plane...but with an added keelson, chines and knees at the stem and transom, if the hull shape is sufficiently stable to float upright, we can probably do something useful with it. Glassing the inside of the planks around the frames is the easy part. IF the wood is sufficiently dry, that is.

James McMullen
03-04-2012, 10:55 PM
Do you honestly think that is the best use of time and effort, Bob? Not to mention the money it will cost? The more I consider it, the less optimistic I feel about the eventual outcome. I don't see how you can efficiently get where you need to go from building off of this foundation. I'd make this a kid's play fort and start over fresh, myself.

Dont feel too bad, Bo. I've built dozens and dozens of boats, and some of them were real stinkeroos. I've sunk plenty of time and money into dead ends too. I really just want you to have success and be delighted with your own first one.

wizbang 13
03-04-2012, 11:06 PM
Do you honestly think that is the best use of time and effort, Bob? Not to mention the money it will cost? The more I consider it, the less optimistic I feel about the eventual outcome. I don't see how you can efficiently get where you need to go from building off of this foundation. I'd make this a kid's play fort and start over fresh, myself.

Dont feel too bad, Bo. I've built dozens and dozens of boats, and some of them were real stinkeroos. I've sunk plenty of time and money into dead ends too. I really just want you to have success and be delighted with your own first one.
plus 1

Rich Jones
03-04-2012, 11:08 PM
I wish James was around 40 years ago when I designed (at age 18) and built my first sailboat. Ended up looking like a sailing cigar box with a pointy end. Although it floated and sort of sailed, it didn't last long and was a lot of wasted material and time. A very harsh life lesson.
Start anew with a proven design and learn to love woodenboat building!

Bob Smalser
03-04-2012, 11:23 PM
Do you honestly think that is the best use of time and effort, Bob?

I think that's Bo's decision, not yours. To make it he needs facts, not editorials.

Further, this level of negative pile-on is excessive, and what makes me occasionally regret participating here. A fella has the initiative to build a hull using his own ideas instead of the usual Ply-Goo-Boat-Plans-Dot-Com cookie cutter, and rather than use our experience to advise him how to make it work, we rudely tell him to scrap it and start over. While I have some concerns about the amount of deadrise given the hull's lack of shape and flare, given the level of existing progress, tacking a bottom on it and tossing it in the water for a test float before further time and effort is expended passes my common sense test.

Bob Smalser
03-04-2012, 11:24 PM
plus 1


Pot. Meet kettle.

You should be the last guy here to diss unconventional ideas and questionable execution. No tape to reinforce those skinny, plywood-to-plywood seams? I'd have commented earlier but I never could come up with anything positive to say. Namely, to puzzle out a lanyard to keep that 40hp motor from maiming you if the bow banana-peeled at speed.

http://farm4.static.flickr.com/3399/4647294007_1c2bbbf72c_z_d.jpg

But I understand it's now a moot point as you lost control and wrecked it on the rocks running a motor half that size.

Glad nobody was hurt. Grace of God and all that.

L.W. Baxter
03-04-2012, 11:48 PM
Maybe think about double planking. Another layer of quarter inch, epoxy glued, with the joints staggered. Glassed on the outside, and inside between frames, I wager it would be very stout; maybe on the heavy side but not going to fall apart.

DMLugoDC
03-05-2012, 01:03 AM
Dtsman: I dont mean to be disparaging, but in the content of whatever books you state to have read, Did any of them give detailed accounting of the REAL and VIOLENT forces that an outboard motor can exert on a transom? If so, have you personally done any reasonably accurate calculations to determine the ammount of "beef" your mounting will need to sucessfully handle a motor at full throddle in rough water under full loads? You state that you copied the hull shape from plans. Did you also take into account the framing and building methodology that went along with those plans? If you liked the hulls enough to copy them, why didnt you just build the boat according to tested plans? It really does sound to me that you went cheap with materials and will try to remedythat with glass and epoxy. EVERYTHING I have ever read on this site reccommends just the opposite. Use the best materials you can afford and you'll be able to rely less on glass and epoxy. It seems to me that some of the members here are trying to be as polite as thay can, trying to have you take a deep breath and learn from what seems to be an experiment in miscalculations. But you are a full grown man. Go nuts and build your dream. Just remember. Darwin Awards are usually given posthumosly.. You dont want one...

wizbang 13
03-05-2012, 02:01 AM
Pot. Meet kettle.

You should be the last guy here to diss unconventional ideas and questionable execution. No tape to reinforce those skinny, plywood-to-plywood seams? I'd have commented earlier but I never could come up with anything positive to say. Namely, to puzzle out a lanyard to keep that 40hp motor from maiming you if the bow banana-peeled at speed.

http://farm4.static.flickr.com/3399/4647294007_1c2bbbf72c_z_d.jpg

But I understand it's now a moot point as you lost control and wrecked it on the rocks running a motor half that size.

Glad nobody was hurt. Grace of God and all that.

Bob, I am not dissing the IDEA, i am advising against continuing with a lousy lookin "design/ construction",the cedar "planking" is lousy wood.
In Wizbangs defence, the tapeless seams did not fail, I did not loose control,* the next one will be 30 pounds lighter. not moot at all as wizbang always was a proto type that took 60 hours to build for 300 dollars and logged almost 4000 miles before she hit the rocks.


* I was not watching where i was going for 20 seconds," loseing controll ",well, that would be tripping, flipping, or, as you say, diving. She just plain ol ran ashore.

wizbang 13
03-05-2012, 02:03 AM
Maybe think about double planking. Another layer of quarter inch, epoxy glued, with the joints staggered. Glassed on the outside, and inside between frames, I wager it would be very stout; maybe on the heavy side but not going to fall apart.
double epoxy planking GOBBLES up glue. That would be an easy 3 more gallons

Bob Smalser
03-05-2012, 02:24 AM
In Wizbangs defence, the tapeless seams did not fail, I did not loose control,* the next one will be 30 pounds lighter. not moot at all as wizbang always was a proto type that took 60 hours to build for 300 dollars and logged almost 4000 miles before she hit the rocks.


The flip side of my comments is that Whizbang is an adorable design that only needed a minor joinery upgrade or two for long-term, vibration durability and a more-appropriate, 7.5-15hp motor to be a great boat harking back to the days of the wonderful, "Popular Mechanics" boat plans many older guys grew up on. Well done, sir.

"Bo", and his ilk are kinda the same thing, who will do much better learning from their own mistakes with a little guidance rather than being browbeat into cookie-cutter, plywood-and-goo submission.

James McMullen
03-05-2012, 02:25 AM
Bob, and Bo, I am honestly trying to be as helpful as I possibly can. I am most definitely not disparaging the initiative. But I sure as hell wish I had been around to give myself this sort of advice a few too many times in my own past. It can take at least as much or more time and cash to build a crappy, under-performing or dangerous boat as it takes to build an excellent one.

wizbang 13
03-05-2012, 02:26 AM
http://farm5.staticflickr.com/4103/5066385192_de4e947f6a_z_d.jpg Now THIS was a clapped out 30 year old boat,http://farm7.staticflickr.com/6101/6353232475_7917a94cd5_z_d.jpgThat sails today and is held together with only epoxy. no stem stern keel metal or fg tape. An old carvel boat, doing what can't be done. (according to common knowlege here) But she was made of good wood, brown silver bali, not fast growth red cedar. Chap wants to build a wacky boat, swell, but better mayerials are called for.My wacky boats are not built of poor materials.

Gib Etheridge
03-05-2012, 02:27 AM
I'm surprised nobody has warned you about the design flaw regarding your keel assembly. The first time this hull comes down off of a wave the bottom is going to split right up the middle. There's nothing there to prevent that. You can put all the plywood and glass you want on that frame and it won't help.

Sorry mate, I just can't not warn you.

Try starting a new post asking for design ideas and giving as much information as possible regarding intended use and expected conditions, your location, budget, etc. There are some really good power boat plans available, you'll be much more pleased with yourself.

I'd swear this is a troll except for the pictures. Still not sure.

I wise man learns from other's experience.

wizbang 13
03-05-2012, 02:30 AM
7 1/2 to 15 hp?? !!!!
ah ha ha ha ha aha ha ah ah ahhahaha
just kidding, the 40was too much,( 50 mph), but the 25 was perfect!!

Sayla
03-05-2012, 05:05 AM
The adhesion between boards was stronger than the boards themselves, having been restrained by the frames - I imagine the boards (at 3" - planks not strips) were not dry as well - when you lay a timber floor, you avoid joining the boards together, as they are all restrained by joists (frames) - when people use a two part paint that adheres boards together you can hear "crack" and "bmmfff" all the time come the dry season - the adhesion between the boards is stronger than some of the boards (they split) - cedar has lower shrinkage than a lot of woods, but still, it does shrink

Bob Smalser
03-05-2012, 09:36 AM
7 1/2 to 15 hp?? !!!!
ah ha ha ha ha aha ha ah ah ahhahaha


Or whatever size is sufficiently small so as not to dismount from the transom and go swimming. That can get expensive when they are running, eh?