Glen-L.com

Andy, your build is looking good. Keep up the great work.

Thanks for the tip GD! I'll try something like that.

Thanks Bill.

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Andy Garrett

"When all else fails, follow the instructions." -Dad

Ya' know that sinking feeling in your gut that comes around when you realize something has gone wrong in your build--maybe even REAL wrong?

Well..., I have a problem.

I started fairing at the transom and all went swimmingly until I got to frame 4 (that's the dash board frame), and it only got worse from there forward. More in a minute...

Mind you, I had done as the book indicated and notched my chine at the frames to indicate the bevel required. I used my level as a straight edge as I made nice lines between the chine and the center line of the keel. I used a hand plane, rasps, and a 3x18 belt sander with 40g belts. I went a little deep in a couple of spots creating what the book calls 'hooks', so I marked them for back-fill later on.

So, back to frame 4. The book indicates that "a considerable amount" may need to be removed from the frames when fairing. Frame 4 will loose the batten notches I pre-cut (like a rookie) completely. That's a full inch or more at the deepest! Can that be right? It must be, because that's the only way it's going to be faired properly. However, this is the least of my problems.

I also decided to use the 'Rabl method' of fairing up front. Understanding that the plywood will be sections of a cone arching toward the junction of chine and stem, I set my carefully placed notches. This was when I realized I had an issue.

Going forward from frame 4 to 5 1/2, I saw that the forwardmost frame would also be loosing a "condiderable amount" of wood. So be it, while I had not yet done the deed to frame 4, I decided to follow the Rabl method and fair frame 5 1/2. As I went forward, I stopped using my level, and started using a wooden yardstick (after ensuring it was indeed a straight edge). This way, I could use the rigid edge or the wide flat so it would twist if needed as the plywood will do.

Between the forward frame and the bow, everything went 'pear-shaped'.

It was at this point that I saw that my chine seemed too far inward. I could hold the straight edge from stem to chine to sheer and see that the line terminated inside the contour of the laminated sheer. Mind you, I triple laminated the sheer in this section to ensure I had enough sheer to work with. Turns out..., I still don't.

I checked everything. Set up merasurements, contour and twist of the chine, angles, etc. I can't find anything I did wrong! Yes, the chine went in easier than I expected, but I checked my work carefully with the photos of many other successful Zip builds. It looks right. So do the sweeping lines of my sheers and chines. I can't figure it out.

Here are some photos that may help you see my issue:




You can also see the notches on the center frame that will not be there anymore when faired.

My options as I see them:
1. Change the contour of the stem dramically in order create the proper relationship between the affected members. My remaining stem will be pretty thin! I've already ground away several screws--some in their entirety!
2. Laminate another one or two 1/2" strips on the inside of each sheer between the stem and first frame and trim it down to a small tringle. This may not be enough from looking at it.
3. Flatten my chine back out with the sander and laminate a full size chine onto the existing one between the stem and the first frame. Taper it to the existing chine at the frame and the stem while leaving it full thickness at the midpoint.
4. Some combination of these options.

Suggestions?

Sorry for the book!

_________________
Andy Garrett

"When all else fails, follow the instructions." -Dad

Andy,

Fairing is really tough to visualize, its an art to do well and I certainly never mastered it but I think my model building helped me here since I had at least done it on a small scale before.

Your stem and sheer look fine. The chine and maybe some framework seems to be where the trouble is. Did you take off significant material from frame 5-1/2 between the stem/keel and the chine? If you place the end of a flexible yard stick or other long flexible batten against the sheer/frame 5-1/2 joint (simulating that being already faired) then flex that batten up along frame 5-1/2 only holding the batten at the sheer, chine and keel and letting it flex naturally between those points and you end up with big voids in the frame that is the start of your issue. Those frames should still concave outward a bit when faired. Here is one of the few pictures i have of that area faired. You can see if you bent a yardstick at frame 5-1/2 holding it only at the keel, chine and sheer its a fairly constant concave radius from keel to sheer where the frame would be touching the yardstick along the entire route.
https://picasaweb.google.com/vupilot/Ch ... 3112589890

I think you might need to graft in some frame material to 5-1/2 to build that back up. Take a pic with a batten taped across it and that will show us if that is really required.

Onto the Chine. In the second picture it bends in compared to the sheer and is getting quite thin. Once you build the frame back up it will be below the frame also so I think you will need to graft another log of chine material like you said and taper it past frame 4 at least on the outside and perhaps maybe inside but Im not sure that will be necessary. You want to get that chine to follow more like the contour that the sheer does but not quite that pronounced. It shoudnt be flat like it is or "dish in". Mine slightly dishes in and I did not catch it until I had planked and I had to fill that area later before paint. As seen in this picture. https://picasaweb.google.com/vupilot/Ch ... 2385453378 Another reason why my waterline is not a true waterline. Almost everything added near the end of the build covers up one of my mistakes.

Dont fret, its only wood, you can add more again if needed. Hopefully some more folks will offer their advice as well. Im just one guys opinion and I've only built one of these. I dont want to see you have to take on more work than you need to in order to get it fair.

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My Zip build log...
http://www.vupilot.blogspot.com
http://picasaweb.google.com/vupilot/Chr ... O0x7SvsQE#

"Nothing screams poor craftsmanship like wrinkles in your duct tape."

I figure the chine "problem" is a result of the chines landing too high (or in this case - down) on the stem. I had the same problem (or challenge). As you can se on this picture the hull shape is slightly concave in the very fwd section.



There was a void between the chine and the bottom ply, which later was filled with thickened epoxy.

Frame number 4 will be allright if you mount the battens. Don't fair, make sure the battens are above the frame when in place. The bottom ply is to be fastened to the battens, not the frame.

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You'd be surprised if you added every extra cost that isn't much in the "big picture".

Trying to follow your explanation, I'm a little slow at times.

Sounds to me like you were using a 'straight edge' running keel to chine to get your chine bevel. Between the transom and frame 2 this is fine because the hull shoud be 'flat' in this section, both for and aft and side to side. Forward of frame 2 the hull definitely starts to become more and more curved and you should NOT be using a straight edge keel to chine, but rather a flexible piece of wood or ply wood that follows the original curve in the bottom frame sections.

It looks to me like you 'faired' the 'bottom' of frame 5 1/2 in a straight line - WRONGO! You need to rebuild the original curve into frame 5 1/2. The bottom of the hull should start curving forward of frame 2 and continue to get more and more curved as you go forward. The bottom of the hull should NOT be a straight line forward of frame 2!

Also, looking at these and earlier photos it seems to me that the keel is NOT notched into frame 4, if this is so this is wrong, the keel should definitely be significantly notched into all the frame bottom sections. I cannot envision having to remove 1" or so off the frames!!!! I cut all my notches long before I mounted the frames and all went well.

Your sides should also be 'curved' and NOT straight lines between chine and shear. I used pieces of ply clamped chine to shear to stem to figure out my 'fairing', I've posted a photo of my build similar to your photo of chine/shear/stem. I think this photo shows where I was starting to add a layer to my chine to get it to curve outward more between frame 5 1/2 and the bow. I still have my side and bottom meeting in a concave instead of convex shape about 6" in from the very bow but can live with that.

Sounds like time to take a step back, take a deep breath or two or three, and recheck everything again. You can most always 'add' wood to get things back to where they should be. I've added my share. Patience and good luck.

Keep in mind that from the photos you have not started fairing the shear yet. The sides of the shear will be faired to follow the angle/slope of the outside of frame 5 1/2,so a lot of material will be removed from the shears, particularly the underside of the shear (ie. the edge that on top with the boat upside down).

_________________
This is my first, last and only boat build.

http://www.gdzipbuild.blogspot.com

Adding a few more photos since a picture is worth a thousand words.

The first photo is of my epoxying another 'layer' onto the chine, I hope in this photo you can see that frame 5 1/2 still has it's original 'curve' on it's bottom, but that the forward edge is faired as the hull ply start sloping 'up' towards the top of the stem at this point, but that the back edge of the frame is as made and installed.

The second photo gives you and idea of how much gets faired off the shear at frame 5 1/2.

The third photo shows how I used pieces of ply running from keel to chine, SITTING ON TOP OF THE CURVED FRAME BOTTOM, to determine the angle to fair the edge of the chine. There's a mocked up piece of ply atop frame 4 and atop of frame 5 1/2.

It's a tough nut to swallow for someone that's been a carpenter for years, but had to accept that in boat building

ain't nothing plumb level or square.

And in case you are going HUH? - and noticed the weird looking keel - well I made my keel and skeg as one piece, You can see how the ply I'm using to fair is captured in the groove I machined into my "SKEEL" (combo skeg and keel).

Hope calmness prevails and things take a turn for the better.

I remember coming in the morning after epoxying my chines in place and while admiring my work realized I had shifted the frames side to side by excessive clamping pressure in the wrong places - OOPS!!!! Took a while to calm down and address that kaffufle.

The road to wisdom is simple to express,
To err, and err and err again,
But less, and less, and less. "Grooks"

_________________
This is my first, last and only boat build.

http://www.gdzipbuild.blogspot.com

Andy,

I agree with GD, it doesn't look like your keel is in a notch at #4, and it should be. Also, something I missed in my build, is the keel should be 1" finished, while most everything else is 3/4" finished. I had to build up my keel with 1/4" lamination to match the notches I had cut from the plans. Lastly, and I don't know how you correct this, I think your chine lands too far up towards the deck end of the stem. I had a hard time determining exactly where is should land and ended up using a 1:1 scale ruler on the plans to determine the correct spot. Landing it further down (toward the bottom of the boat) is much harder, introduces a lot more twist, but also creates the hull shape you are looking for. If I get a chance to get to the shop today I will try to do the "take off" again and get you some reference measurements.

As others have said, it's only wood and we all had to do some adding and subtracting to get it right. It won't show when the hull is on. You are making great progress, a step back before the next two steps forward won't make much of a difference in the length of the build.

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My Webalbum: http://picasaweb.google.com/Buckeyesmith1/Gem#

The best part about a manual screwdriver is not needing to remember if you left it in reverse.

Completion is but one step in the process and not one bit more important than the others.

First, I want to thank everyone for their help. I really appreciate it, more than I can express.

The keel is notched at 4. It is only partially notched because I could not get lumber wider than 6" and the plans are about a half inch wider for that member. What you are seeing is the two small missing 'triangles' where the frame would be notched for the limbers. I will add this material when I do the battens.

Now, I have read the 3rd edition of Boatbuilding Wth Plywood (at least the sections which apply to my build) no less than a half a dozen times leading up to this project. One of the key points about sheet plywood boats are that the hulls are sections of a cylinder or a cone, because plywood cannot form compound curves. However, that is exactly what this design requires if the advice I'm getting is correct (which I am certain is the case). The hull is forming a radius in two directions at the same time and using the rigidity of the frame to force it and 'torture' the plywood into a shape it is not supposed to be able to achieve. Page 162 and 165 of the book talk about how such 'hard spots' create a stress concentration. Yet, there it is--right there in the plans. It seems that this set of plans violates or at least stretches the rules a bit in order to achieve its shape. Ok. I accept that. I can build 5 1/2 back up and re-fair a bit.

Don't even get me atarted on the 'Rabl method', which started this mess. Every step outlined on pages 165 and 166 are seemingly disastrous to this design (even if it shouldn't be). Unless..., a builder just wanted keep those flat sections for the entire bottom. Believe me. I considered it.

So, the curvature is a small issue really. The chines are another. I studied the plans carefully and thought I got them placed well. This may not be the case (I should have gone with the chine blocking I was considering). I think I will do as mentioned earlier and laminate some material to my chines to bring the curve out a bit. The last thing I want to do is mess with the sheer shape. I can live with flatness in the bow sections up to 18" back or so, but concave would just be hard to build!

Bear in mind, the hull will be white, and this is not a speed boat. A safe cruising speed between 25 and 30 is fine as long as it trims well and doesn't porpoise.

Thanks again to everyone. I think I have my head around what needs to be done now. My week long vacation of boatbuilding is over, as I go back to work at 11P tonight. It's back to 'time as available' for me on this build. Progress will slow down--giving me time to work this out smartly.

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Andy Garrett

"When all else fails, follow the instructions." -Dad

Tortured is an excellent description of what you have to do to the ply on the hull. When fitting mine it started with disbelief, that this can't possibly conform to the shape of the frame, but figuring if it worked for others it should work for me, I plodded on and eventually found that - hey - it can fit! A long time after that I finally realized that it mattered which side of the piece of ply you were trying to fit you fitted first - yet another frustrating and painful part of the 'learning curve'.

At least with age I have finally managed to get a bit of patience, the luxury of being able to look back and laugh at previous events that I thought at the time were disasters, and now seem like just a life lesson learned. Unfortunately we grow too soon old and too late smart, tis a truism that youth is wasted on the young!

_________________
This is my first, last and only boat build.

http://www.gdzipbuild.blogspot.com

It vcan, and it's mentioned in one sentence in the book you refer to that this will occur in the very fwd section of the bottom.
Cannot remember which page as I cannot find the book right now.

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You'd be surprised if you added every extra cost that isn't much in the "big picture".

Whistler, I looked for that passage but didn't find it. Nonetheless, I'll take your word for it as it is clearly the case anyway.

I just went through and studied every Zip build in the arcvhives and found that there is a wide range of mounting points where the chine/stem junction is concerned. This has created a variety of shapes in the finished boats--all very attractive. Mine is well within the range, so I won't be doing anything as drastic as remounting those (shudder). I'll just add two thin laminations I think from stem to somewhere between 5 1/2 and 4. I'll taper those to 'zero' and let the width swell where it needs to be.

Of larger concern is the keel. Since I used the 'Rabl method' (Rabl is now my favorite swear word), I faired the keel down pretty good. While I'm confident it would be strong enough, I've decided to go ahead with a technique that I've admired on Mark Shipley's build. He put verticle stiffeners on the backs of his keel and battens up to frame 4. They look like 3/4" by 1 1/2" members 'Td' into place which has to add a great deal of strength and rigidity. I will do this on my battens and perhaps go to 3/4" x 2" on my keel. I may even sandwich two together for the keel and go all the way from transom knee to Stem junction (a little curvature needed up front). Then I can level those off and add the sole nice and low in the boat.

I am encouraged. Thanks again everyone!

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Andy Garrett

"When all else fails, follow the instructions." -Dad

Sounds like a good 'recovery' plan. I added stiffeners or strongbacks to my keel and all 6 battens. I made mine 5/8" thick by about 1 3/8" high, it's the height or depth that gives you the stiffness, not the width of thickness of the strongback. Besides stiffenening the battens, I will run my floor slats side to side mounting them to the top of the strongbacks, which will add additional stiffness since one batten won't be able to flex without flexing it's brethren. In the one photo you can see where this will give me almost 4" of extra depth in the boat as opposed to running deck boards on top of the frame bottom member.

There are no problems, only sulutions we need to find.

And do add the stiffeners/strongbacks BEFORE you install the bottom ply !

_________________
This is my first, last and only boat build.

http://www.gdzipbuild.blogspot.com

Did you screw and glue those Carpenter, or just glue?

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Andy Garrett

"When all else fails, follow the instructions." -Dad

Just thickened epoxy and lots and lots of clamps! I really can't see screws adding any strength beyond that of epoxy from all that I have read. Besides, those dang brass screws strip out if you look at them wrong. On top of that I didn't want to have the luck of having an exisiting screw holding the stiffback exactly where I inevitably want to screw down a deck boad.

_________________
This is my first, last and only boat build.

http://www.gdzipbuild.blogspot.com