Author Topic: Alternative Build Order  (Read 29970 times)

Offline Spokaloo

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Re: Alternative Build Order
« Reply #15 on: February 25, 2009, 09:39:54 AM »
Im going to throw a wrench into everything here...



I finished a Mertens designed LB22 last year (the first of her kind) using his method, and I can say that a Tolman is possible to build, and this method has MUCH to offer...

The difference being you just would do the bottom panels one of two ways:

1) Attach the stringers before the glass, then lay the sheets of glass in long, linear pieces outside and inside the stringers.

This method will allow a better bond between the stringers and the bottom panels because it would be a molecular bond to the wood instead of a mechanical bond to the already-cured fiberglass in the method Renn uses. It is also much the same as the method used in Carolina Sportfishers, where the wood is joined to wood, then glassed accordingly.

2) Build exactly as Mr Mertens describes, by creating the hull as a shell, then rolling it over and lifting ALL of the interior structure out, glassing, and replacing it after glass.

This is how I built the above boat, and it worked flawlessly. The entire bottom of the hull is laid in only two sheets of fiberglass, one on each side, overlapping the fairbody seam by 6" both sides and the chines by 6" both sides. It allows more tape to be used more effectively, and has fewer places where a mechanical bond is the only bond.

Im going to have to say you could give it a shot. If you want more details on the method, I wrote a start-to-finish blog on the construction of my boat, and the method is heavily detailed step by step with photos.

http://buildingnina.blogspot.com

I have given thought to the same idea because of how it seems every builder has to horse his hull panels down to the stringers, where my stringers literally fell into place perfectly and the hull came out incredibly fair.

E

Offline AlasKen

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Re: Alternative Build Order
« Reply #16 on: February 25, 2009, 09:50:39 AM »
Also the hull shape improves after horsing it to the stringers. 


That is a good point. 
« Last Edit: February 25, 2009, 10:49:09 AM by walknbob »
Kenneth Dodson
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Offline Spokaloo

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Re: Alternative Build Order
« Reply #17 on: February 25, 2009, 10:46:22 AM »
Quote
Also the hull shape improves after horsing it to the stringers. 

Its that horsing that concerns me. Shouldn't the bottom panels be the right shape from the beginning?

Also the broken stringer issue that has reared its head a time or two can be attributed to a low bond strength allowing the stringer to flex independently of the bottom panels.

Don't get me wrong, I am still very much contemplating building a Tolman using Renn's methods as soon as I am done with this kitchen remodel, just want to be clear on all accounts when talking about various build methods.

E

Offline walknbob

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Re: Alternative Build Order
« Reply #18 on: February 25, 2009, 10:49:59 AM »
Also the hull shape improves after horsing it to the stringers. 


That is a good point. 

OOPS... I accidentally hit modify instead of reply with quote to Ken's message... So most of his comments we deleted by accident.

Sorry.
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Offline kchace

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Re: Alternative Build Order
« Reply #19 on: February 25, 2009, 11:21:16 AM »
Quote
Also the hull shape improves after horsing it to the stringers. 

Its that horsing that concerns me. Shouldn't the bottom panels be the right shape from the beginning?

Also the broken stringer issue that has reared its head a time or two can be attributed to a low bond strength allowing the stringer to flex independently of the bottom panels.

  This has been brought up before. The consensus was that the stringers are the correct shape - the bottom panels need to be bent in a very complex shape and will bend differently depending on the species of wood, panel density, humidity that day, etc. So it is necessary to 'pull in' the bottom panels to the stringers.

   I have to disagree about the cause of a broken stringer - at least as it relates to a Tolman. No-one has EVER shown a broken stringer in a Tolman. If my recollection is correct - Renn once "heard of" a case of a cracked stringer in a Jumbo and from then on specified LVL lumber for stringers.  If you ever have stringers flexing independently of the bottom panels, then you have a serious problem and a broken stringer will be the least of it.

  After glassing both sides of the stringers to the bottom with the 24oz biax as Renn specs, there is a really good tie-in. That 24oz biax is thick and very very tough stuff. 2 layers of it is about 3/8" thick.

  Ken

« Last Edit: February 25, 2009, 12:03:16 PM by kchace »
Ken Chace
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Offline kchace

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Re: Alternative Build Order
« Reply #20 on: February 25, 2009, 11:29:35 AM »
But the side panels, would it make sense to glass the inside of these after the hull is assembled and flipped?  I think I saw one build on the site where it was done that way.  It seems to me it would be much more difficult to bend these if the inside is glassed.

  The side panels will flex ok enough provided that one only glasses the inside before attaching to the hull. In my case, I did not do this because I did not have the room to build the boat AND lay out the sides to scarf and glass. I did what several others have done and "scarfed them on the boat". I then glassed the sides after they were installed. There is NO WAY this is easier or faster or (IMO) better - especially when you're trying to apply glass on the inside up near the bow, but I didn't really have much choice.  The way the sides are done, you end up making them a bit bigger, test fit and mark them when on the hull, trim to just a little oversize, then re-attach with glue and do a final trim.

  Just for the record - In my opinion, while a direct glue bond to bare wood may be best, a properly done epoxy bond to cured epoxy is PLENTY strong.

  Ken
« Last Edit: February 25, 2009, 11:50:20 AM by kchace »
Ken Chace
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Offline jklistof

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Re: Alternative Build Order
« Reply #21 on: February 25, 2009, 12:22:04 PM »
Fiberglass the insides of the sidewalls first, I can't imagine not doing that part first.

John
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Offline mschlechter

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Re: Alternative Build Order
« Reply #22 on: February 25, 2009, 12:34:49 PM »

  The side panels will flex ok enough provided that one only glasses the inside before attaching to the hull. In my case, I did not do this because I did not have the room to build the boat AND lay out the sides to scarf and glass. I did what several others have done and "scarfed them on the boat". I then glassed the sides after they were installed. There is NO WAY this is easier or faster or (IMO) better - especially when you're trying to apply glass on the inside up near the bow, but I didn't really have much choice.

I had the same situation as Ken for space, I did glass the inside pieces first though and then "scarfed them on the boat". Then just placed some glass over the scraf and faired it. Ohhh.. I did do the forward scarf before placing it on the boat, I only did the back one on the boat. I am not sure how I found the space, I must have done it before I assembled the jig and all the pieces.
« Last Edit: February 25, 2009, 12:36:43 PM by mschlechter »
Mike
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Offline pfithian

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Re: Alternative Build Order
« Reply #23 on: February 25, 2009, 02:09:47 PM »
Im going to throw a wrench into everything here...

I finished a Mertens designed LB22 last year (the first of her kind) using his method, and I can say that a Tolman is possible to build, and this method has MUCH to offer...

The difference being you just would do the bottom panels one of two ways:

1) Attach the stringers before the glass, then lay the sheets of glass in long, linear pieces outside and inside the stringers.

This method will allow a better bond between the stringers and the bottom panels because it would be a molecular bond to the wood instead of a mechanical bond to the already-cured fiberglass in the method Renn uses. It is also much the same as the method used in Carolina Sportfishers, where the wood is joined to wood, then glassed accordingly.

E

That is what I was thinking, not sure why this would be so hard.  Nor can I see right now why it would be so hard to glass the inside of the sides after flipping, especially if I do not place the vertical 2x4 frame members until after it is glassed.  It would be the same angle as when glassing them from the outside, and it would allow overlap to the taped joint between the side/shelf and side/chine.

By the way, E, that is  one gorgeous boat!
Made It Jumbo 25
Skiffkits No. 7025 1/2009
Build Start:  3/2009
Hull Flipped: 1/31/2010
Maiden Voyage:  9/16/2011

Offline AlasKen

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Re: Alternative Build Order
« Reply #24 on: February 25, 2009, 03:20:35 PM »
This will be my last post on the subject.  If you are still talking about the bottom and stringers the difference is there will be crap in the way.  When are you going to attach the transom to stringers?  The only way you are going to be able to glass the bottom is top crawl around in the hull while glassing.  You are either going to have to do one section at a time and wait for it to cure or you are going to get crap in it by moving around.  It was a pain in the back to glass the bottom when you could get to both sides and roll or spread epoxy  I know how much my back hurt just doing the fillets on the stringers.  I would never consider doing it that way.

If you are referring to the sides I will also say it will be much more work to do it after they are in place for the same reason that it was more difficult to do the out side of the side than the insides.  You are working on the vertical instead of flat.  Epoxy runs down hill.  You will also have the gunnel shelves in the way as they have to be in place.  So instead of being able to stand up straight and spread epoxy on a flat surface you will be on you hands and knees spreading it on a vertical surface.

Do it however you want to but if you are looking for the easiest way with the least amount of effort on you back and knees follow the book.  There are many ways to accomplish the same outcome.  Pick whatever works for you. 

I was right where you were.  I wanted to do it my way and felt that I figured out ways to make it easier and less work.  After I tried everyone of them I realised why the book was easier.  Pretty soon I just followed the book.  However go for it.  That is half the fun.
Kenneth Dodson
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Offline Spokaloo

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Re: Alternative Build Order
« Reply #25 on: February 25, 2009, 08:15:41 PM »
Ken there is absolutely no arguing with the fact that it is easier the way Renn does it.

Some of us are wired a certain way and can't help it. I tend to err on the side of building light and strong, so I prefer to get 110% out of every bond so I can make her lighter later. Thusly Id love to do the interior wet on wet. Mind you, my boat was stringer over cured epoxy, so obviously the discussion there is more theoretical.

On the interior glassing...

I found that I liked working wet on wet, and this particular method would be easily suited to the Tolman as described at the beginning of the thread. She would be built upside down, using the various parts of the interior as a jig. The chine shelves would need to be supported in a different fashion than the plan, but thats easy enough, Pull up from the jig or across from the stringers. Where it would get really interesting is that she would be glassed, faired, and painted upside down while on the jig. Then turned, emptied of her contents, glassed inside, and all the guts replaced and glued up.

Rolled:



Taped:



Glassed:



Guts:



The best reasoning for this isn't because its easier. Its not because its faster. What it does is create a more ACCURATE shape in the hull right away, instead of relying on brute force to bring the hull into submission. It would also alleviate one of the issues Ive read about in various build chronicles, the hard spot in the bow. Without building the bow separately, you can glue up the second piece of 1/4" the day after you weld it together (this will require filleting inside, obviously not easy, but accurate), and it wouldn't be out of the question to tape or sheath between the panels if you so chose.

As for the transom attachment, its easy to pull two pieces of plywood, cut to the appropriate angle, and either attached to the stringers or the jig to hold the transom. Ideally, however, you would stitch it to the hull just as you would any other piece. It would be a part of the hull and the side panels from day one, preventing the chance for a hook to develop in the bottom.

Again, Im not saying this is THE way to build. Im just giving an example that PF isnt that far out of whack in thinking that he could build a damn good boat in short order using this method. For the first ever build, it might be better suited to do it more to Renn's method, but if you have any experience at all in fiberglass, you can actually move FASTER on hanging panels at less than 90 degrees, because the epoxy spreads itself.

BTW, thanks for the compliment, its been a fantastic boat for our lake, just a little low sided and not enough cover for the weekender/ocean thing.

E

Offline pfithian

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Re: Alternative Build Order
« Reply #26 on: February 26, 2009, 05:26:19 AM »
One slight difference that I am thinking from what E describes above with the Bateau/Mertens method, where everything is removed from the inside of the hull before glassing.  In my suggestion, the bottom would be glued to the stringers and transom, the sides installed, and the entire outside would be filleted, taped, and glassed.  I would also fillet, tape, and glass the joint between the sides and shleves.  Except for the shelve to side joint, there would be no glass on the inside of the hull before flipping.

After flipping the hull, the stringers and transom to bottom/side joints would be filleted and reinforced with 1708 Biax, then fillet/tape the bilge, chine to bottom/side, and bow stem to bottom/side joints.  I would then lay 5 sheets of 6 oz cloth, running lengthwise, in the following order:
1)  Port side to chine
2)  Chine to outside edge of port stringer
3)  Between stringers
4)  Chine to outside edge of starbord stringer
5) Starboard side to chine

What has caused me to think through this are some lines in Renn's book that I can't get out of my head, they are on Page 63 under the section on Secondary Bonding:

  "Epoxy-to-epoxy gluing is called secondary bonding.  Epoxy sticks to wood well because it sinks in and gets a grip; it follows, then, that it doesn't stick to cured epoxy as well because it can't sink in.  Avoid this situation when you can."

Also, further down in this section:

  "It is best to glue to cured epoxy within 72 hours, in which case there will be some chemical bonding."

The way I am suggesting, virtually all joints and cloth would be applied within this 72 hour window.

I can't disagree that it would be easier to glass panels while they are horizontal on the sawhorses, but I have to get in the hull anyway and glass the stringers, so why not do the rest of the bottom and side panels while I'm there?
« Last Edit: February 26, 2009, 05:28:54 AM by pfithian »
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Offline mschlechter

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Re: Alternative Build Order
« Reply #27 on: February 26, 2009, 06:28:47 AM »
I am with Ken here, this is my last post on this.

You can build it any way you wish, no problem. I am sure it will all work out fine in the end. Yes, a wood to wood bond would be stronger, yes, Renn suggests that also. Why did he not build it that way then? Because I do not think it matters one hoot in the long run, it will all be strong enough if done properly. Remember, his success at the numbers of boats he built, how many structural failures do you see?

Again, I have no problem with how one ones to do it, lots of ways to skin the cat. I do have a problem with asking about doing it different and then this need to convince others that it is the best way. If it is the way you want to do it just do it then.

Yes, I think you are over thinking, but if you want to that is fine. We all went through that, some reason we all think we need to improve on or build stronger then what is specced. Few of us will probably use our boat more or harder then Renn has done.

Ask for advice, take it or leave it, start building, however you want, in the end it will be a fine boat that you will be happy with.

Sorry for the rant...
Mike
Juneau, Alaska

Offline kchace

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Re: Alternative Build Order
« Reply #28 on: February 26, 2009, 06:34:23 AM »
  Primary bonds are definitely stronger, but epoxy is so strong to begin with that there should never be (and to my knowledge has never been on any Tolman) a problem with a secondary bond. Its simply so good that its not an issue. Hell, they build polyester boats with secondary "tabbed bonds" to the hull. THEY don't fall apart and everybody knows that polyester has much poorer secondary bond strength than epoxy.

  So it won't be easier or faster, but you're not convinced of that. Having been there, I know better. The bonds may be a bit "stronger" and that's of course fine. As far as the rest goes, I'm with Ken D. You have to do it your way - so go for it and don't look back. You'll end up with a great boat either way.

  Ken
Ken Chace
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Offline Spokaloo

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Re: Alternative Build Order
« Reply #29 on: February 26, 2009, 09:01:58 AM »
Mike and Ken, I don't think he is trying to convince you of anything. Like all of us, he needs to air out his ideas, vetting them against a few people. Ironically the gents here at Fishyfish tend to be a bit more Alaskan than most other forums, and take the conversation as an affront.

Nobody is denigrating the method. Renn perfected what he found to be the fastest and lowest effort method to build a skiff for his way of thinking. Others may consider their way better for reason X, Y, or Z. There is no upward turned nose, or sidelong glare at his method, but there are views here that don't mesh with new ideas on construction.

PF, I think you are definitely better served by doing the stringers as you suggest. If they are all mated up and glued before the turn, it will be a stiffer structure to roll. Just remember that you will need to be able to glue those to the bottom panels somehow when setting them, so figure that step out in the process. Im not sure how it would be accomplished personally. Maybe you have an idea.

Do keep in mind that you can also work port side-stbd side-port chine to stringer-stbd side to stringer, then lay the glass right up the middle and hop in. Wearing socks you can lay the glass in and walk on it while you work from the bow to the stern laying epoxy down. It actually works really well, and I put both of those sheets of glass in during a 7 hr glassing shift.

Again, everyone should be willing to give input on this, but definitely give personal experiences, as that will give PF so much more to think about. "while I was building mine, I did ________ and it made more/less work"

E