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Thread: How I build Mahogany Runabouts (in pictures I hope)

  1. #51
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    I planked my runabout using a diagonal ply planking for the first layer and it did work very well. If i could just get the nest step done.... lol

    Always something of higher priority coming up. I really gotta get on it...
    Tom

  2. #52
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    I give you top marks Dale for the attempt, but after seeing that warped ply in place, i didnt see how that was going to turn out fair. I think what you have decided to do is right, as there is only so much you can do with ply.The thinner pieces you will know be working with will be far easier to deal with. Look forward to your progress.

  3. #53
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)



    Ok, this is how I should have done it. I added a 1x 1.5" chine and 2 1x1/2" battens to each side. The Fein multimaster tool is just excellent for notching into frames. The new framing is beveled and epoxy coated. Ready for skin.

  4. #54
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)



    In this picture I have cut 6" sections of Baltic Birch 1/4" plywood and am fastening them at a 45 degree angle to the longitudinal frames. I'm using thickened epoxy to hold the planks which have been set in place with 3/4" pneumatic nails. This technique is very fast. The Baltic Birch has 5 plys and since I cant get Ocomee, its the best substitute I've found.

  5. #55
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    [IMG][/IMG]

    and here's how it turned out- way better than the full sheet method. There is some fairing to be done and for this I'll use Bondo. Remember this is core for the epoxy laminate- its only function is to support the glass/epoxy/ chopped strand mat which is next to come. It will never see water. Keep that in mind before you condemn the use of Bondo.

  6. #56
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    Today I scraped thickened epoxy into the seams of the diagonal planks. Tomorrow I'll Bondo fair the outside planks.

  7. #57
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    QUOTE=Dale R. Hamilton;3575359]Today I scraped thickened epoxy into the seams of the diagonal planks. Tomorrow I'll Bondo fair the outside planks.[/QUOTE]

  8. #58
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)



    This shows that I've faired the planks with Bondo and sanded them smooth. I've learned that you can't wait until the final sages to fair- indeed, it must be done at each stage. This picture also shows the first layer of bottom in place. This first layer is scarfed to 16', laid in wet epoxy and then shot with 3/4" pneumatic nails. The second and final layer of Birch will be but jointed and fastened with 1" screws through both layers.


  9. #59
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    Will the topsides be mahogany planked? If so, how thick will that planking be?
    Tom

  10. #60
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    OK, Dale....... Time to get back to work, man....... Christmas is coming, and I expect to see this baby under my tree with a big red bow on it......
    Never trust a man with a clean workshop.

  11. #61
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    ok sorry for the long pause. I was on a cruise around Spain and the canary Islands, then a trans Atlantic passage. But back in the shop and here's what I've done


    http://im1.shutterfly.com/media/47a2...D550/ry%3D400/

    The double bottom is on. The sides have been faired with bondo, and now am fiber glasing the whole structure with 6 oz Eglass. The seams and the chines have a double layer of 6' tape. After the glass cloth has cured to the green stage, I'll go back and fill the weave with epoxy and then squeegee Peel ply into the wet epoxy. This gives a smooth mat surface. I will fair once more then prime and paint.

  12. #62
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    The first layer of 6 oz glass cloth is on, the weave has been filled with epoxy and its been faired. Now comes the second layer of glass. Its 53" wide and I cut it long enough to go from just past the keel centerline, over the chine to the edge of the sheer. Optimally this is a 2 man job, but of course, I do everything alone. Here's the method I came up with. Tape edge of the cut material to a 2" PVC pipe the same width as the cloth. Swab the hull with epoxy and then lay the rolled material into the wet epoxy just past the centerline. Now, just unroll the cloth keeping some tension between the roll and the laid cloth'



    When the cloth is rolled to the edge of the chine, go back and fill the weave with a foam roller and epoxy. Don't worry about the small bubbles (now).



    Next take a plastic spreader (like used with bondo) and squeegee out all the bubbles working them to the closest edge



    Now you can run the rest of the cloth roll over the chine and overlap the sheer. Repeat the steps listed above. When the entire hull is fully wrapped and dried, you will roll on 1 or 2 more epoxy coats to completely fill the weave. Then guess what?- time to fair again. As I've said, I've found this to be necessary at every step. Hope to prime next week- I'll send you a picture.

  13. #63
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    Forgot one last step. When you roll the last coat of epoxy over your hull, I've found it helpful to lay peel ply into the wet epoxy as before. This reduces the tendency to develop raised bubbles and it produced an even mat finish.

  14. #64
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    I'd like to see a picture of the peel-ply step, if you've got one. I've heard about this a number of times, but I'm not sure I understand what "peel-ply" is or how you folks use it.

  15. #65
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    Good Morning Dale,

    Welcome back from your trip, sounds like a great time. Thanks for taking the time to keep this thread going.

    Regards, John

  16. #66
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    Peel Ply is a layer of 2.7 oz. Dacron fabric strips or tape laminated into a layup as if it were an extra ply of glass. The peel coat wets out with epoxy like glass cloth and cures along with the rest of the layup. However, the Dacron does not adhere structurally to the glass and when peeled away it leaves a surface ready for glass-to-glass bonding without sanding. Poly/Dacron blend is excellent as peel ply for composite lay-ups. I'll send you a picture although its exactly like the cloth.

  17. #67
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    Another trick to pass on. When you are laminating glass cloth you will invariably get bubbles, epoxy-starved areas, and raw selvage edges. Here's a dandy example:

    The way I fix these is to use a die grinder with a course Roloc disc as shown. Grind off the bubble or rough edge of the cloth like this:



    The Roloc disc is fast and it tapers the side of the crater which a knife cut would not do. Then mix your epoxy/cabosil putty and apply with a squeegee. I use a mixing pad on a palette which is a stack of chemical-proof paper. You mix one batch, use it, and tear off the top sheet to expose a new sheet. (See www.mixingpadsusa@aol.com). These are available at most auto paint stores. Lots of good things we can find at these places.


    Finally, it should look like this:

  18. #68
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    The last step after the glass cloth has been completely filled is the application on one more coat of epoxy with Peel Ply laid into the wet epoxy just exactly like you laid the glass cloth- except you don't need to cover it with wet epoxy-EXCEPT and unless you see dry areas under the ply. If this is the case, roll more epoxy over the dry area until you see it wet. The epoxy will roll right through. Here's what it should look like;



    Notice no dry spots. Give it 24 hrs to dry and then pull the peel ply off. It has done its job and should leave a uniform mat surface, Like this:



    The laminate is now complete. Two layers of 1/4" birch ply epoxied together, two coats epoxy, two coats 6oz glass cloth, weave of both filled twice, and a final coat of epoxy set in peel ply. That makes a bottom that's pretty much bullet proof. Now comes final sanding and filling any little dings that surface. I'll report back after I've laid down several coats of high build primer.

  19. #69
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    Nice. A trick I have learned from glassing over 20 wooden kayaks and canoes is to heat your shop to over 80 degrees, apply your fiberglass and epoxy, and then cool the shop down to 65 degrees as quick as you can. The air in the wood will contract and suck in the epoxy. If you epoxy in the morning and the temperature rises over the day, the air in the wood will expand and outgas through the fiberglass. It gets worse when you have covered one side with fiberglass and then glass the other side, the air has no where to go but out the fresh side. I also roll on a thin precoat about 8 hours before with 1/8 nap foam roller made for epoxy use. This helps the outgassing by sealing the wood.

  20. #70
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    Thats an interesting point. I would have thought that was only an issue on "real" timber and not on plywood? Im assuming you are talking about cedar? I believe some people use a heat gun for the very same purpose which may be fine to lay on an initial sealer coat before glassing. For those of us who work in "well ventilated" conditions, a poly tent is the only way to raise heat, but a good way to cool down fast.

    Looking good Dale. Do you use any special kind of cloth for your sheathing of the bottom? E/S glass Bi/Tri laminate? Cheers

  21. #71
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    Standard 6 oz E glass.

    So, here's a picture after two heavy coats of primer:
    As you can see I use Omni MP282 plus 283 (fast) hardener shot with a 1.0 nozzle on an HVLP gun. After two coats dry, I sand out with a longboard using 80 and then 180 grit. Then fill the little nicks and what not, sand again, and shoot two more coats. Finally I'll sand with320 grit on a Rotex sander. It is now ready for color, which I will shoot as soon as I can get the paint booth temp up to 50 degrees. the shop is heated but when you turn on the big paint shop blowers, it quickly blows out the heated air. More later.

  22. #72
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    Gotta love hi-build primer.

  23. #73
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    Ok here's how she looks with primer sanded out with 320 grit. I didn't intend to, but I did go back over it wet sanding with 400 grit. I know it does not make much sense for the bottom- but he gloss is worth the effort. Finally 3 coats of black base coat and two of clear coat. Next comes the mahogany veneer transom. I'll try this as soon as I can gather about 6 additional hands to help.

  24. #74
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    How much time do you spend keeping your shop surgical clean? I would feel uncomfortable letting rip with a router in that shop! Carry on.

  25. #75
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    I tidy every day when I finish, with the big sweep down at end of each stage. Then mop periodically. Dust is my enemy- must keep after it. All the dust chutes of my shop machinery are fitted with electric leaf blower motors which blast the machine dust outside- and the little creatures take it home. Even my big planer producec no dust

  26. #76
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)



    Here's the finished transom. I bonded 3M backed ribbon mahogany veneer with Weldwood contact cement onto the transom. I had 3 guys for help which is critical. When in place I rolled it flat with a veneer roller. Then stain with Minwax Sedona red cut 50% with Minwax natural. Then I shop 3 coats of clear coat, sanding out with 320 grit and then wet sand with 600 grit. I applied the vinyl boot stripes. Then I shot 2 more coats of clear over the entire transom including the stripes.

  27. #77
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    Time now to tip the hull form the rotissary into the Yardarm dollyies for completion. Here's what it looked like.


    The bottom looks pretty good- ignore that uneven reflection. Next step jack the hull high enough to allow the dollies to lie under.


    Now its just a matter of unbolting the hull from the building jig and allowing it to drop into the dollies. Finally you have this.



    Now its easy to fillet the internal seams, and do everything else that would have been done upsidedown.

  28. #78
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    Is it just the colour or is that below waterline section below the stripes looking a bit hollow and bumpy? Have to commend you on your extraction system,worth every penny when they work well.

  29. #79
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    Have you used this type of veneerin this appliction befoe? When you say 3m backed is that with th epsa adhesive or some type of pheniolic backer instead of paper?

    I would be very wary of using any paperbacked veneer or any kind of contact cement on anything where water contact is an issue, much less a boat.

    Maybe I am overly conservative on this but my choice in this instance would be a soild wood veneer, maybe 1/8 or so thick, epoxied in place and stapled or vacuum clamped until the glue cures. Staples could be removed or left in palace.
    Tom

  30. #80
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    Answers: The stripes are quite smooth- I see what you mean. its just the camera angle.

    Its also a solid wood veneer - not 1/8- more like 1/32, and it comes with 3m STICKUM. I don't really trust it so I use weldwood in addition. Nothing will unseat this bond. And when its coated with 4 coats of clear, its impervious to water. Remember this is transom- it will get wet but its not underwater. I've done exactly this on 4 boats and they are just fine.

    Agree vacuum clamp would be ideal. I've tried this several times but can't seem to master the technique. Glad somebody is reading this stuff.

  31. #81
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    Reading, and enjoying!

    Tom

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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    So, you apply the Weldwood OVER the 3M adhesive that is already on the veneer? I'm not challenging, only confirming. I was thinking of a similar stategy for a transom of a trailer-bound runabout. Does the veneer also have some sort of fiber backer, or is the 3M adhesive ITSELF fiberous? What is your source for that veneer? Thanks!

  33. #83
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    Richard- yes, Weldwood is applied over the adhesive already on the veneer. Not sure its needed, but I do it anyway. The veneer is supplied with some kind of paper backing which makes it much easier to handle. The veneer came from A&H Turf of Billings, Mt- a 2X8 sheet african ribbon mahogany goes for $44.31. Can also get it frpm Woodworker Supply and Certainteed.

  34. #84
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    The motor and outdrive are now installed. The motor is Mercruiser's 3.0 liter TKS 4 cylinder- a 135 hp hotor that has been in production since 1962. The outdrive is an Alpha I mercruiser. There will be a lot of room in the engine bay so it should be easy to work on. And I will make the hatch large enough to pull the enging should that ever be necessary.

    Next step is to plank the hull with 3/16's mahogany plank. This stuff was acquired by Higgins Boat builders during WWII to plank PT boats. When the war ended, some 3000 board feet went to a warehouse in Alabama- where it stayed for 70 years- until I bought it. So now I've selected enough to plank both sides and now I'm coating the glue side with 2 coats of epoxy to keep the adhesive from being drawn into the wood. When dry I'll run them through a belt sander so the good side will get a head start on being smoothed.

  35. #85
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)



    Here's what the planks look like freshly coated with epoxy.

  36. #86
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    3000 bf of mahogany! Nice score, glad to see you putting to use. Has it split much over the years from drying out?

  37. #87
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    Properly aged, huh?

  38. #88
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    Quote Originally Posted by Tom Robb View Post
    Properly aged, huh?
    There's a little splitting on the ends- so I loose 3 or 4 inches off the end- still its 6' long. This stuff is nearly 50" wide- yes 50 inches- which means the trees must have been huge. Probably none like these left on the earth.

  39. #89
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    Unfortunately theres still stuff like that being illeagally logged. We had some baulks 40in wide at a top end yard i used to work at,but it was hard to source even then. So much stuff was ripped into 6in planks and was exported as "floorboards" including 2 nail holes in each end of the boards.....you know its wrong when you get timber shipped like that.

  40. #90
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    This is the stage I find most satisfying- hanging the Mahogany planks. I know this is a perfect application for the vacuum bag technique- and i own all the equipment necessary including the vacuum machine- but I just can't manage it. It takes too many hands, and I only have two. So I fit and hang each piece one at a time. In this picture, I've coated both surfaces with 3 coats of Weldwood contact cement. You need something that is aggressively sticky- and Weldwood certainly is. Some spiling is necessary on some pieces.



    When its in place the next step is to roll the hell out of it with a J roller as I'm doing. The slightly open seams will close up some.



    Finally, I shoot 5/8" brads every 4" along the edges, which of course will have to be filled with epoxy fairing compound. Finally, all will be sanded smooth and fair starting with 80 grit and ending with 400. More later.

  41. #91
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    I am finding this build more than interesting, it it so different to orthodox building.
    I would never thought of using contact cement on a boat hull.
    You must work exacting tolerances for the panels, laying them so precisely that they fit 6 foot down the line.
    I have trouble positioning Formica on a flat sheet.

  42. #92
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    bahma- if my boat building methods are unorthodox its because I never had the benefit of boat building instruction, and Murfreesboro Tennessee is not exactly a hotbed of boat building art. Instead I come form the 'trial and error' school. For example, I'm not using vacuum bagging because I've tried it a dozen times and experienced catastophic failures every time. Now if I had 3 guys standing around to help, it would be a different story.

  43. #93
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    Thanks for (as they say in math class) "showing your work." I would like to see detail of the intersection of the veneered transom, the gunnals, and the bottom. I'm assuming the gunnals will be painted and the transom left bright. I'm specifically curious as to how you manage the fiberglassing (taping?) at those intersections. I'll also be curios as to how you apply and treat the exterior keel and if you glass over it.

    Also, have you ever used Pliobond contact cement? I read that it is superior in a number of ways - including water resistance. It also has a couple of ways it can be applied and activated. I've done experimenting with it, including soaking and the dishwasher test. I does hold up - showing no signs of release. The problem seems to be availability in larger containers. Do you have any thoughts or experience with Pliobond?

    Anxiously standing by . . .
    Last edited by Richard Smith; 03-25-2013 at 07:01 AM.

  44. #94
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    I cant imagine using contact cement for joining planking on a boat. Has anyone talked to the manufacturors about this application. From any experience I have with conact cements the glue line isn't rigid enough for structural use. i would be afraid of creep or disbonding when stressed. It seems you could acheive the same results using epoxy.

    What type of brads are you using. Stainless? if not are you concerned with rust eventually. Im sure this will be epoxy coated and varnished but thats a lot of faith to put in a finish.
    Tom

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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    Quote Originally Posted by Richard Smith View Post
    Thanks for (as theyin math class) "showing your work." I would like to see detail of the intersection of the veneered transom, the gunnals, and the bottom. I'm assuming the gunnals will be painted and the transom left bright. I'm specifically curious as to how you manage the fiberglassing (taping?) at those intersections. I'll also be curios as to how you apply and treat the exterior keel and if you glass over it.

    Also, have you ever used Pliobond contact cement? I read that it is superior in a number of ways - including water resistance. It also has a couple of ways it can be applied and activated. I've done experimenting with it, including soaking and the dishwasher test. I does hold up - showing no signs of release. The problem seems to be availability in larger containers. Do you have any thoughts or experience with Pliobond?

    Anxiously standing by . . .
    I'll post more pictures when I'm finished staining and clear coating. The bottom and the hull up to the waterline are painted, then mahogany planks. I tape over the junctions of bottom and sides with 3 layers of cloth then sand down the edges of the tape to make them disappear. I have not heard of Pliobond but I'll look for it. The Weldwood works just fine- never had an issue of delaminating. Remember the whole hull will be sealed with at least 4 coats of clear.

    There is no keel, the bottom is slick and smooth. However I will be laminating up spray rails and rub rails. I'll show you that in a few days.

  46. #96
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    Quote Originally Posted by Tom Wilkinson View Post
    I cant imagine using contact cement for joining planking on a boat. Has anyone talked to the manufacturors about this application. From any experience I have with conact cements the glue line isn't rigid enough for structural use. i would be afraid of creep or disbonding when stressed. It seems you could acheive the same results using epoxy.

    What type of brads are you using. Stainless? if not are you concerned with rust eventually. Im sure this will be epoxy coated and varnished but thats a lot of faith to put in a finish.
    Tom- I've never had an issue with debonding or creep. I usually use nylon nails shot from a pneumatic gun- they are really tough and even come in dark brown color. And remember, these "planks" are just 3/16" thick, so they are more like veneer

  47. #97
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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    Quote Originally Posted by Richard Smith View Post
    Thanks for (as they say in math class) "showing your work."
    Ditto that.
    We must go too far in order to know how far to go. Yeah.

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    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    I had a great amount of difficulty removing a linoleom floor in a wet room/shower,that had been stuck down at least 10 years ago with contact cement. I dont know how many varieties there are, but the timber floor underneath was bone dry. Something similar is still used today installing new linings in wet rooms. Just saying, epoxy would work too.


    Hows that Bently purring?

  49. #99
    Join Date
    Mar 2001
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    Murfreesboro, Tn. USA
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    1,580

    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    Quote Originally Posted by skaraborgcraft View Post
    I had a great amount of difficulty removing a linoleom floor in a wet room/shower,that had been stuck down at least 10 years ago with contact cement. I dont know how many varieties there are, but the timber floor underneath was bone dry. Something similar is still used today installing new linings in wet rooms. Just saying, epoxy would work too.


    Hows that Bently purring?


    Bentley is purring along just fine. I thought about buying a Rolls, but I decided that would be ostentatious.

    Epoxy would be my preferred adhesive naturally, but you need something that is aggressively tacky. The panels must be radiused around the hull and epoxy wouldn't hold it until it dried- like in 8 hours.

    Reading the Weldwood can it says its resistant to water and the longer the bond time, the stronger it will get. I too have tried to pry off a misaligned panel and it is very difficult- even when the glue isn't fully dry

  50. #100
    Join Date
    Jun 2000
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    Douglasville, Ga
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    2,327

    Default Re: How I build Mahogany Runabouts (in pictures I hope)

    I understand what you are saying about the tack and initial grip of contact cement, but I have never seen a weldwood contact cement product that is considered a structural adhesive, which i would think this application most certainly is. The rascal runabout is built in a similar manner but the planking is all epoxied inplace, held with stainless staples which can be remover after cure or left in place.

    Not trying to rain on the parade, just never seen this type of adhesive used this way, and i would be wary of long term durability.

    The weldwood contact cement spec sheets I have read specifically say it is non structural. I don't even trust my interior veneer work to contact cements after seeing some fairly spectacular failures, and that's with 1/42" thick veneers. I use urea formaldehyde glues for all my veneering and am using epoxy on the boat build.

    I probably tend to err way on the side of caution, but that could be the aircraft mechanic in me....
    Tom

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