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  1. #1
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    Default Goat - new build in Seattle - and a bottom panel question

    Hello,

    I started my build a couple weeks ago in Seattle. I have cut out the side panels and the bottom panels. However, in my exuberance get going on the bottom panels I forgot to leave the extra 20mm. I remembered the 20mm halfway through my cut on the stern side, so the bow side does have the extra. In general how much of this 20mm buffer on the bottom is planed off after the bottom is affixed?

    I am hoping this is no big deal . . . is it?

    Other than that I have nearly all the materials for the hull and things are coming together smoothly. I hope to start on the bulkheads shortly.

    Thanks!

    Joe

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  3. #2
    Join Date
    Feb 2013
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    New London, Minnesota
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    Joe - Welcome to the Forum. I wish you no bad luck, but I'm glad you ask the question because I am about to go where you are and want to know what happens when I goof. Good luck on getting together.

    Jerry

  4. #3
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    Howdy,

    Cut to the original size the bottom will go roughly to the inside edge of the side panel plywood. But also the 20mm is because we are never quite sure of the exact shape the boat will take.

    I'll say it first but it is not the only solution - if you have the dough and it is convenient you can save a lot of time by buying two new sheets of ply.

    That is the easiest most straightforward solution.

    However if that is not practical or affordable there are a couple of ways around.

    I would dry assemble the sides and bulkheads but then dry fit the bottom too. I will run through the method below...

    SETUP - like a lot of the goat building this part takes a long time to explain and not so long to do.

    The objective is to make sure that any gaps are not toooo big and force the chine logs to take the design shape much more accurately than normal.

    When attaching the side panels to the stem put a very large piece of ply as a pad on the screw through the side that is closest to the bottom. There is a lot of load on this one when the boat is assembled and you are going to be quite active on the part assembled boat. It's on the outside has to overlap the beginning of the chine log on the inside by a couple of inches (50mm) min.

    It might be too fiddly doing the bevels with a plane .. a way to reduce the wobbling movement would be to put two temporary braces diagonally across the hull from chine log to chine log at about 45 degrees to the bulkheads. Bevel the chine logs as in the plan for the bits that are accessible then move the diagonals and finish it off.

    Now the bottom is ready to go on as a dry fit too. Do the centreline and bulkhead screws.

    You will very likely need someone to help for the next stage (though if the ply bottom lines up with the inside edge of the side ply in most places then you don't need to do this next stage.

    But if the bottom ply is a long way from the inside edge of the side panel ply you can force it into place and put a temporary screw 19MM/3/4" OR 25MM/1" through the bottom into the chine log. REMEMBER THE CHINE LOG IS NOT VERTICAL AND THE SCREW WILL HAVE TO ALIGN WITH THE REAL ANGLE OF THE CHINE LOG.

    Do this where necessary to get the alignment needed. If you start with the worst areas and do them first then it might pull into shape with very few screws. That's an important aim. Use the minimum number of screws and check these criteria.

    • We can't alter the width of the boat at any of the bulkheads - not by much - so the areas to concentrate on are between the bulkheads.
    • If the ply edges are less than 3mm 1/8" apart I would be pretty happy.
    • The distance should vary in a smooth way - if there are sudden increases or reduction in the distance you will have to adjust something to keep the curve of the sides fair.
    • Gradual changes are good.


    Next you have to mark where the screws are so you can see when the boat is upright. Pencil marks on the outside of the chine or better pencil marks on the chine logs on the inside of the boat. You can do this with the boat upright or upside down.

    CAPTURING THE SHApe - there's a trick to this type of work. Just go slowly and gently and take your time. Don't rush or feel you have to make up time in any way. The results will be pretty good if you just go through slowly.

    Now we have to capture that shape so the bottom can be taken off.

    The way I would suggest is with the boat turned upright that you put temporary pieces of wood from the top of the chine log inside the boat in the screw positions and run them to the other side of the boat.

    There are two ways to do this.

    1. If you have a screw on both sides of the boat at that location that means the degree out of shape is symmetrical. So the temporary brace can go across the hull from chine log top to chine log top. My guess is that most of the problem will be to pull the sides closer together - so a strip of scrap plywood an inch 25mm wide will work fine. One screw in each chine log. If it was really tough pulling the sides together in some location then you might need wider ply and two or three screws into the chine log.
    2. If the screw is on one side only then the distortion is asymmetrical. Use a plywood strip like before and it goes from the screw position on the problem chine log to the other side just adjacent to where a bulkhead meets the chine log. Choose the closest bulkhead.


    When this is done you need to control the load at the bow end. I would cut a piece of ply a trapezoidal shape so it fits between the chine logs about 200mm back from the bow. Giving you 200mm space to the back of the stem. It will need to be wide enough with the ends cut at the right angles to take three screws per side into the chine log. They will need to be about 1" 25mm

    Remove the screws into the chinelog through the bottom working from the stern end forward and make sure there is no huge movement as the chinelog as they come undone.

    Ok ... now you are ready for permanent assembly and you have caught up with yourself!

    PERMANENT ASSEMBLY -Again work slowly - you have several hours before the glue is too rigid. But it all should happen in one straight through session. Have a pack of biscuits handy and non alco beverages and a walk is not out of the question if you need to clear your head for 10 minutes.

    Make sure the hull is level and untwisted as per this stage in the plan.

    Some builders already depart from my plan by pre assembling all the bulkheads and hull sides then removing the bulkheads one by one. In this case you are going to follow their method starting with the bow. This method tends to be a bit messier (maybe) so I would put masking tape either side of each bulkhead leaving a 6mm 1/4" margin and do the same behind the stem. Also I would put very clear lines in pencil aligning with the back face of the stem on the side panels. If that matches all will be well.

    The first thing to remove and glue in is the stem. Assemble everything in the same holes as far as possible. But it might be difficult - so the target is the pencil guide line you just drew. Don't clean up the excess epoxy yet.

    When happy with the stem move onto Bhd#1. Draw pencil guide lines before removing it including the position of the top of the bulkhead. Try to hit the same screw holes if you can see. Otherwise do the pencil lines.

    When happy Clean up the epoxy ooze from the stem area.

    next bulkhead, clean up epoxy ooze from the previous bulkhead. etc.

    On getting to the transom "congratulations!!!"

    Have a final search for epoxy ooze then remove masking tape.

    Final thing as per the plans is to temporarily clamp or screw the gunwales in position to make sure the top edge of the hull is fair as all the epoxy starts to cure.

    Next work session you can fit the bottom. If the bottom has moved a bit you should be able to push it back MAKING SURE EVERYTHING IS A SMOOTH CURVE BY LOOKING AT THE GAP BETWEEN THE BOTTOM PLY AND SIDE PLY.

    When the bottom is on ...

    FILLING THE GAP IN THE CHINE.

    Masking tape either side of the gap to be filled and using the piping snaplock bag method to fill it.

    A method used for surfboard repairs comes to mind. You could use several layers of masking tape on the side panel to make a dam that comes up slightly higher than the bottom - then pipe the epoxy/thickening powder mix into the dam. Not sure how it would work.

    The big mistake that everyone initially makes with filling holes etc is they smear epoxy all over the plywood either side of the filled area as if they are filling a screw hole in a house. DOUBLE DON'T!!! It if far better to leave the epoxy with area required to fill the gap or hole only and let it bulge above the surface. This way you have the minimum area to sand off compared with smearing a pseudo flat area of epoxy for lots of area around the hole or gap.

    Then sand a nice radius as per the plan. Refill touch up if necessary.

    When it comes to glass taping I would be happier to see two layers of glass. Put a 50mm 2" one on first followed by a 75mm 3" one. Or if you were 2oz (75gsm) glassing the bottom panel as a few have elected to do - unnecessary but I will mention it here then that can form the second layer if it goes about 37mm (1.5") around the chine.

    Whew ... hope that helps.

    Michael

  5. #4
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  6. #5
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    Michael - thanks for the detailed response!

    I was hoping it wouldn't be an issue, but it seems it will take some extra effort to work around. I checked out the bottom panel again today and figured I would see if a little more detail would lead you to believe won't be as much of an issue.
    GIS Bow.jpg
    You can see in the picture that the port side of the bow bottom panel has the extra room. And most of the starboard side of the bow piece does, too. The only real trouble spots are the starboard side close to teh tip of the bow(pictured) and close to the rear end of the front panel on the starboard side. Each of the real bad spots have at minimum 5mm to spare.

    The entire stern piece has the full 20mm, and I haven't yet joined the bottom panels, so really, worst case I think I could get away with buying just one more sheet of ply. I haven't cut into the last two pieces of ply (the sheets for bulkheads and seats, etc). I thinking that I could turn the botched bow piece into the front seat, use one of the uncut sheets for a new front bottom panel (and center case 2, bulkhead 2, and hopefully bulkhead 3) and then I should be able to get the transom, .
    mid seat and rear seat out of the sixth panel.

    Right now I am leaning towards the option in the last paragraph, but . . .

    Given the extra space you see in the picture does it lead you to believe that it might not be as troublesome as it might have been?

    I would much rather save time starting fresh with new cuts rather than have to deal with extra epoxy and fiberglass work.

    Thanks again for all the info!

    Joe

  7. #6
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    That extra 6mm will make all the difference. If it doesn't eliminate the need to push and shove as per my instructions above it will certainly minimise it.

    I would definitely try the bottom as cut now and see how it works out ... you might be able to shuffle it backwards and forwards too or even select a new centreline.

    I very much think you will get away with it or almost so.

    MIK

  8. #7
    Join Date
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    MIK's suggestion to try shoving the bottom back and forth refreshed my recollection. Unless the plans/instructions have changed there should be 4 or 5 inches of excess length at the stern that is trimmed after installation. Those extra inches might save the day for you. It's certainly worth trying a dry fit to see exactly what you will be facing.

    Good luck!
    The "Cosmos Mariner,"My Goat Island Skiff
    http://s176.photobucket.com/albums/w168/MiddleAgesMan/

    Starting the Simmons Sea Skiff 18
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  9. #8
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    Yes .. there is a lot of extra length at the stern end of the bottom panel. I always put that in my designs just incase.

    So with the extra width you have on one side and the extra length there are quite a few possibilities.

    Just remember that you do need a centreline in the end. Whether it is the one I stipulate or a new one doesn't matter.

    MIK

  10. #9
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    Glad to hear I can keep chugging along. Thanks again for the extra info. I did leave the full excess on the stern, per the plans, so I think I will be ok.

    My little baby girl was born early Monday morning so I have lost a little focus on the boat (and been exhausted)!

    I am lucky to get a lot of time off work, so the next 2.5 weeks will be filled with the 4 Bs: Baby Bonding and Boat Building! Maybe start back up on the bulkheads a bit tomorrow.

    Joe

  11. #10
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    Not at all sad about this type of delay to boatbuilding Joe.

    Congratulations and best wishes to your wife and family on the successful launch of the baby into the world!

    Michael

  12. #11
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  13. #12
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    You will probably want to delay marking the centerline on the bottom panels until you've made the adjustments to compensate for the forgotten extra width. Shoving the after piece forward a little (using some of the extra length) will also let you shove the forward panel forward. You can then shift the forward panel to one side to equalize the excess trim material. That is where a centerline marked too early could come back to bite you. Once you've worked out the final position via a dry-fit, mark the center at the bow and stern then snap a chalk line to connect the two marks.
    The "Cosmos Mariner,"My Goat Island Skiff
    http://s176.photobucket.com/albums/w168/MiddleAgesMan/

    Starting the Simmons Sea Skiff 18
    http://www.flickr.com/photos/[email protected]/

  14. #13
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    Default Goat - new build in Seattle - and a bottom panel question

    IMHO I think he can just shove the panel around and get it to fit, then screw and glue and shave it to fit. THEN the center line gets to be important, and easy enough to snap a line on.


    Sent from my iPhone using Tapatalk
    Dave
    StorerBoat Builder, Sailor, Enthusiast
    Dave's GIS Chronicles | Dave's Lugs'l Chronicles | Dave's StorerBoat Forum Thread

  15. #14
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    Quote Originally Posted by davlafont View Post
    IMHO I think he can just shove the panel around and get it to fit, then screw and glue and shave it to fit. THEN the center line gets to be important, and easy enough to snap a line on.


    Sent from my iPhone using Tapatalk
    I think screw and glue here means the butt strap. And then draw the centreline.

    The centreline has to be approximately right though or the bulkheads will be displaced giving a misreading of the widths. Probably not a lot, but who knows. So to fiddle it around until it fits. Mark the centreline location at the bottom join, the bow and centre of the transom. Take it off then use a string line to check all the points match up. Then double check after the centreline is on.

    MIK

  16. #15
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    Thanks for all the advice. I've starting chugging along on the bulkheads so can inch closer towards seeing if there will even be an issue when the bottom goes on.

    Bulkhead #1 Question:

    I've got all the framing cut and clamped into place. I just want to double check a couple of things. The sides of the ply piece are a bit rounded, so when I attach the side framing I tried to get as much flush as possible with the ply, and there are overhangs elsewhere (especially at the top). Is this right? I am assuming I just plane the framing on the sides to the curve of the ply, and then add the bevel. Am I on the right track?

    Also, on the bottom bevel. It is a 2mm bevel, and on the drawing it looks like you have the bottom framing overhand by 2mm and then do your bevel. The 2mm overhang is explicitly stated for BH #2, but not for BH #1. Just want to be sure which one to do.

    Thanks!

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