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Thread: First build from DN Goodchild plan

  1. #1
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    Default First build from DN Goodchild plan

    Hello all,

    I am planning to build a hard chine motor cruiser the "Compact" I am waiting on the plans from DN Goodchild.

    I plan to build cross planked, with two layers criss cross and the outer layer for and aft, is this a good idea?

    I can buy larch in beams of 150 * 50 mm, I plan to rip it in 50 mm strips.

    What thickness should I rip the strips for the laminating jobs, and what thicknes for the cross planking?

    Note I will rip 50mm because in that case i will end up with more or less quarter sawn wood.

    All advice or tips is welcome.

  2. #2
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    Default Re: First build from DN Goodchild plan

    Hmm,

    50 views and no responses?
    Could there be something wrong with my forum settings so that I can't see the responses to my thread?

    If so please PM me

    Thanks

  3. #3
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    Default Re: First build from DN Goodchild plan

    No responses yet. The first 51 people did not feel knowledgable enough to answer your questions.

  4. #4
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    Default Re: First build from DN Goodchild plan

    I cannot see enough information on the Goodchild site to know how the bottom of Compact is shaped and why you choose to use a layup of two staggered crossplank layers and yet a third one longitudinally. Seems awfully complicated for a boat that is labled "simple to build."

    Maybe that is why you are getting no responses. This is very outdated construction for a powerboat.
    Tom L

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    Default Re: First build from DN Goodchild plan

    I'd imagine the plans come with much of the details you require. If not, or for more information on scantling rules in general, get a copy of Dave Gerr's book, Boat Strength.

    As far as the specifics of cold-molding with larch, there are others aboard here who can answer that question. Be patient, they will be along.

    Kevin
    There are two kinds of boaters: those who have run aground, and those who lie about it.

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    Default Re: First build from DN Goodchild plan

    Hi everybody,

    it is just that I worried that I had somehow s*****d my forum setting so I could not see the replies on my post.

    You now I just think that I'm quit capabale of making this kind of stupid mistake

    I'll continue posting as soon as I receive the drawings.

  7. #7
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    Default Re: First build from DN Goodchild plan

    I had plans for a larger boat from the same designer and it was seam batten construction,i would not have thought this one would be different,though it could be straight carvel. As Tom says, a 3 skin strip hull is an awfull lot of work when it could be done in a single layer,and then possibly sheathed. Was you intending to nail fasten your strips? Some larch is prone to splitting when nailed,and you may need to pre-bore for every nail,otherwise larch is a good planking timber.
    When you recieve the plans , let us know the suggested scantlings, and some knowledgable person here will translate that into an alternative planking method. Generally,but not always, it will be pretty similar or slighty thinner in a glued construction than the original thickness. Doesnt look to be a lightweight boat,inland use or North Sea coast? Cheers

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    Default Re: First build from DN Goodchild plan

    @skarborgcraft,

    Thanks for your reply, it will be a boat for inland use (lakes rivers canals) I like the design because I think it is for cruising at low or moderate speed, but that is assuming on my part.

    I know that triple stripping is a lot of work but never the less I would like to try this tecnique, first because I feel confident that I can do this single handed, and perhaps even more important I think I will have a better possobility to make right the mistakes I am going to make.

    Also I think it will give me a very solid and resistant hull ( the boat is going to be trailer sailed )
    I will not try to cold mould the boat because with narrow strips i can be sure that there is 100% contact between the surfaces.

    A very important thing for me is that larch is cheaper than okoume plywood about 15 euros per sq metre.
    And it is the only rot resistant wood that is affordable for me ( red cedar etc. cost an awfull lot of money) so yes I will have to pre drill all the nail holes, I guess that you can't win them all.

    I must say though that I like the building part the most.
    I have been looking for a space to build a boat for years, and now finally I found one
    Waiting impatiently for the plans to arrive.

  9. #9
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    Default Re: First build from DN Goodchild plan

    With 50mm plank strips, you are probably closer to cold molding than strip building, especially with the relatively thin strips for three laminations. 50mm strips will still require some spiling, probably more than you are thinking and thsi why it may be closer to cold molding than stripping. I would not want to go thinner than 6mm for any of the strips/planks and that will give you a bottom of 18mm which shound be plenty substantial scantlings for this boat. Quite a number of longitudinal stringers will be needed to support the cross planking to prevent distortion and that also makes the bottom even stronger.

    It will make a very strong and serviceable hull but is a lot of work and material. The bottom will also have hundreds of small catch spaces for water and other things that are not good for a boat interior and thus maintenance is increased. One thing that is always true in such construstions is that what the builder is doing is really making their own plywood and if this can be done cheaper, with a suitable waterproof glue, than commercial plywood, I would be very surprised. In a hull that has developable bottom panels, my choice would be plywood and for many others it would be ply sheets for the aft portion and double cross plank plywood for the twisted forward sections that are not developable.

    No matter, we wish you a rewarding experience in building your cruiser. What power and speed range do you anticipate that you will be aiming for?
    Tom L

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    Default Re: First build from DN Goodchild plan

    @ Tom Lathrop,

    I am aiming at a speed of about 7 kmh ( about 5mph) there is a lot of nice boating to do in areas with a strict speed limit ).

    I hope I can stay just below 10 hp.

    I have to do some more googling for speed and power limitations, to be able to cover as many as possible areas.

    As for the glue, everything will be epoxy glued and coated, I have done the math, and the outcome is that there is simply nothing that will match epoxy, for the cost or for the performance.

    For the cost of the plywood versus the triple planked larch, I can tell you that I was quite flabbergasted to, but I spent a whole rainy saturday playing around with a spreadsheat, and believe it or not, it realy is less expensive! Roughly I calculated the total hull surface at about 32 sqr metres * 15 euros (cheaper) that makes 480 euros this money will buy me 4*7.5 = 30 litres of epoxy and I still have 80 euros left to buy the "building beer "

    And I will be prepared to tackle carvel built boats with the same tecnique, the whole project is very much a learning expierience for me, after all I am a first time builder.

    I agree that it is much more complicated and a lot more work, but in the meantime building a simple design with a tecnique like this, would be a sure and save way, to learn. I don't think that this could go wrong.

    If only those @$%&* plans would arrive. Mr postman don't bother to ring twice just drop them plans in that letterbox.

  11. #11
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    Default Re: First build from DN Goodchild plan

    Sam Rabl did a good cruiser called Kittiwake, 24ft, though the beam is slightly over Euro trailing limits.I didnt see what beam the "compact" had?Otherwise similar. Easy planking, Chesapeake style bottom that would be easy to straight plank with your larch. Im not sure if the plans are also availiable at Goodchilds,but "boatbuilding in your own backyard" is avaliable second hand,and will give you all the information you would need to build it. If you have the time and patience to build a triple skin, then a single skin carvel hull with this easily planked boat,could be built faster and cheaper.....admit the downside of regular trailing is best not suited to a caulked seam boat,but if it was only a few times a year,i wouldnt see a problem.

    How was you buying your larch,in rift cut boards or ready cut and sided? Timber normally sold in price per cubic ft or metre, so your price for larch Vs ply is a bit confusing. Cheers
    Last edited by skaraborgcraft; 05-02-2012 at 01:57 PM.

  12. #12
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    Default Re: First build from DN Goodchild plan

    The larch I can buy is in 150 x 50 mm dimemsions, that I would rip in to 6 x 50 mm strips.

    1 metre of that costs 3.95 euros, cut up in strips of 6 mm (counting the width of the saw blade at 3mm) I would cut 16 strips, 16*0,05= 0.8 sqr metres
    0.8 sqr metres * 4 euro a metre = 3.2 euros a sqr metre i need 3 times that (criss cross + for'n aft) = 9.6 euros a sqr metre.
    I have togo to the shop tomorrow to recalculate the price of plywood but I think a piece of 4mm (2440*1220 mm) costs something like 50 euros so that's 16.80 euros a sqr metre, and I havan't even begun to calculate what 18 mm thickness of plywood costs.

    Please correct me if I'm wrong.


    The problem with my "project" is that I'm building it on a shoe string budget.

  13. #13
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    Default Re: First build from DN Goodchild plan

    If this really is a shoe-string budget,then you can save money by not using epoxy and doing it the old fashion way. Theres nothing wrong with decent galvanised nails,screws. Was you considering outboard or inboard power? I think your 10hp is about right,i had a 10hp Bukn in a 7 ton cruiser and it was fine to reach hull speed with some power to spare,if you are considering an outboard,i would suggest looking at 4 stroke Yamaha......but these are not exactly shoe-string budget engines! Cheers

  14. #14
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    Default Re: First build from DN Goodchild plan

    When I mentioned 6mm laminates, it was related to fitting and handling them in the way you want to do it, not for adequate total bottom scantlings. 12mm or even 9mm would be adequate for the boat and speeds you intend to run. Tripple skins in 9mm would get you to cold molding with staples and all that though. There would be no slamming loads at 5kts. Lots of boats with big inboard engines have been successful with only 9mm skins. I would not personally go higher than 12mm unless it were carvel planking, which I think is wrong for this boat and this time. There is always, always, more waste than we plan on when resawing lumber and wase in glue and coatings is not minor either. If you budget is small, build slower as money is available. Building always longer than we estimate anyway.
    Tom L

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    Default Re: First build from DN Goodchild plan

    Yippey I got the plans, we are talking about the same thing, the drawing calls for 3/4inch cedar so I suppose two layers of 6 mm larch would be okay?

    And another question, is it okay to do one layer diagonally and one layer for and aft, or would it be better to have two diagonal layers, thr hull is "flaring?" out quit a bit so perhaps I should go for two layers diagonally.

    Since the ribs are not strait but they have an arch I think I will laminate them in place, (note to self check that on Wizbangs venus ketch thread).

    The glue is going to be Epoxy, here in the Netherlands I cannot find any glue that can match it for quality or even price, epoxy being 10 euros akilo cheaper than any other glue.

    @skaraborgcraft, the boat is designed for outboard power, in the drawing I think I can make out 2 Seagull OB's. and IIRC they were 5h HP max.

    I think the build is indeed going to be slow, because of the small budget I have got. But boy I am looking forward to this challenge.

    This weekend I'm going to convert the offset table to metric, because at my age feet, inches and 1/8 ths are getting me slightly confused.

    The building space has been confirmed today, Roy and I are going to clear out some junk on monday, after that I wil just make a "model" with the station moulds 1/5 scale.
    So at the latest on tuesday the building of the strongback will start. I think this boat is going to be a real "looker"

    Stay tuned, pics next week.

  16. #16
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    Cool Re: First build from DN Goodchild plan

    Hi everybody,

    Rceived my plans and got busy lofting the station molds (scale 1/5) this was quit interesting because there ere some errors and I added some erors myself.

    I really like the looks of it from station # 12 on all the way down to the transom.
    But I really don't care about this extravagant flare (or whatever you call it) from the stem to station #10 and I plan to just join the sheer line directly to the chine line.
    The aft portion of it is way


    I have two reasons for that:

    1) it will symplify building the frames enormously

    2) the most important reason of all, it will look better!

    I don't know how to insert a poll but I would like to hear opinions!!
    So please let me know




    One thing I can tell you, while lurking around this forum I got the notion into my deteriorating brain that lofting is a good idea

    I did loft the stations scale 1/5 and it revealed some errors in the offset table and in applying the batten I could put some of my errors right.

    My firmly implanted idea is to stay with the simplyfied layout for the stations #2 to #8.
    Please let me know what you think.

    Tomorrow I am going to loft the Keel scale 1/5, and monday I'll be shoving around a mega heap of s$$t, and I'll call myself lucky if it's all straightened out monday night.

    Please stay with me, and do through anything you have at me
    Yours Gerrit Jan
    --
    Last edited by beernd; 05-05-2012 at 11:02 AM.

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    Default Re: First build from DN Goodchild plan

    The flare keeps up bouyancy as the bow pitches,and throws off spray. I guess there is no reason why you cant straighten the frames out to join with the chine,its your boat after all and beauty is in the eye of the builder! Having said that,with the thin strips you will be using,it shouldnt be any problem to plank. 3/4 in cedar is 18mm,though you could probably get away with 12mm. You could plank double diagonal,each layer at 45 degrees to eachother, or even double plank both layers fore-aft, diagonal would be stronger. Are you intending to put a lightweight glass cloth on the outside,clear finish or paint?

  18. #18
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    Default Re: First build from DN Goodchild plan

    @skaraborgcraft,
    I will plank diagonal 2 layers at 45 degrees, and having taken a second look at the drawing I think I will stay with the flare.
    There will be no glass just epoxy coating for money and time reasons I will probaly paint, at least the hull, the interior is going to get a lot of clear finish.

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    Default Re: First build from DN Goodchild plan

    Is the timber you are purchasing kiln dried? Just be aware that some larch can be quite resinous,and may cause gluing issues with epoxy. I would stick to the plans myself,thats a nice looking flare. Paint outside and clear inside sounds good. What timber will you use to laminate your frames?

  20. #20
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    Default Re: First build from DN Goodchild plan

    For the frames I intend to use the larch as well.

    If the timber is kiln dried would that be a problem?

    The same lumberyard also sells douglas fir.
    Googling this forum and other blogs, and factsheets about larch I found that larch was very well suited for strip buiding, and that douglas fir came in a wide variety of qualities. I am no wood specialist so I will stick with larch, and european larch seems to come in a rather constant good quality, I have not encountered any red flags about lesser qualities of this wood.

    And I will stick to the plans.
    I might have an El Cheapo adress for boat varnish I will check that out this week.

    By the way would european larch look good when varnished or should I apply a wood dye before appliying the epoxy coat?

  21. #21
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    Default Re: First build from DN Goodchild plan

    Larch looks fantastic clear finished,my folkboat is larch,as is my sail and oar boat,my friends folkboat is still clear finished after 28 years and looking peachy. I wouldnt bother with any dyes. Never come across any laminated larch frames before,oak being the usual material for that due to strength and steaming qualities. How does the fir compare with the larch on price? Long straight grained and knot free fir could be used for the keel timbers,but if your larch is relatively good quality,no reason you couldnt use that.

    Are you going to laminate your frames first or build on moulds and fit the frames after?

  22. #22
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    Default Re: First build from DN Goodchild plan

    The fir and the larch are the same price.

    So it looks beautiful, in that case the hunt for boat varnish is on.

    Today I will start lofting the stem and keel part scale 1:5.
    I will erect moulds and stringers and then laminate the keel and the frames.
    Last edited by beernd; 05-07-2012 at 12:14 AM. Reason: typo

  23. #23
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    Default Re: First build from DN Goodchild plan

    Drawn all the station moulds scale 1:5 tweaked the offset table a little and rubbed out some of my own errors, when I redrew it straight from the correct table everything was as it should be.
    Tomorrow i wil be pushing around stuff in the barn and clear a space for the strong back/building rig.

    Looking forward to it
    Last edited by beernd; 05-07-2012 at 11:34 AM. Reason: typos again, keep doing that

  24. #24
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    Default Re: First build from DN Goodchild plan

    --To day is the day . . .



    --Some pics from the workspace.



    Don't worry the batten is ok it's just a funny distortion in the pic.

    BTW how do I rezise pictures in photobucket, my pics were never this big

    I traced three half frames 7 more to go.

    It's coming together.

  25. #25
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    Default Re: First build from DN Goodchild plan

    You could cut that spiling batten down to 20mm or so and it will be fine,any reason you are using such a deep section? It would be nice to see that plan layout in your picture,the run aft looks to be well raised in that picture,but in your lofting was a flatter run.... could just be the keel im looking at in that plan?

  26. #26
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    Default Re: First build from DN Goodchild plan

    What you are looking at is station mold #2, it should be OK for the lofting I just devide all the values by 5, but I agree it is a bit of an awkward angle

  27. #27
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    Default Re: First build from DN Goodchild plan

    A small misunderstanding. I was looking at the plans drawing in your photo,and thought that the after body in the lines plan was more than in your previous post of your drawn frame sections. I went to Goodchild site and had a look at the drawing,the after bodt does sweep up astern,by i wonder why she has such a flat section at the transom .Hard to see without the lines plan. Are there any power suggestions in the plan?

  28. #28
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    Default Re: First build from DN Goodchild plan

    The power suggestions are either two "B class" or one or two "C class engines" and I don't have a clue to what HP that represents.

    Two B class engines giving the boat a speed of 10 to 12 MPH, while one C class engine gives it a speed of 9 to 10 MPH, two C class engines could make it go as fast as 14 MPH.

    My guess ( being as good as anybody's guess ) is that the B class engines are about 5 HP each.
    One C class maybe 15 HP ?

    Maybe some body might know what these classifications represent.

  29. #29
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    Default Re: First build from DN Goodchild plan

    I think you will find B and C class outboards will be classed by their cylinder capacity rather than horsepower if the little hydroplan classes were anything to go by. Obviously that is why she has the flat sections aft,not a displacement cruiser. I have the plans for the larger "Janet",30ft.
    Could you put up a picture of the hull lines for further study? Cheers

  30. #30
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    Default Re: First build from DN Goodchild plan

    Best of luck with your build Beend. If you are concerned about the epoxy and larch being compatible it seems I read somewhere that a good wipe down with acetone is a good idea before a glue up. If I am mistaken I hope someone will correct me.

    Oldad liking the looks of the Compact

  31. #31
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    Default Re: First build from DN Goodchild plan

    @ Oldad,
    Thanks for the tip!

    @scaraborgcraft

    I was amazed by that flat section too, the whole part below the waterline looks pretty similar to for example Weston Farmers "Sundance" which was designed "to move at a good clip".

    I went by the description of the "Compact " as a "Smart little boat for economical driving" , which in my opnion a boat designed for cruising at hull speed so I chose this design over the "Sundance" also because the "Sundance is only 17' and 6''.

    I will scan and post the lines plan to night.

  32. #32
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    Default Re: First build from DN Goodchild plan

    It will be interesting to see her lines,she seems to have a deep fore-foot. Sundance is a great little boat,but has more "V" in the transom than "compact".

    Oldad suggestion of acetone on resinous wood is correct.

  33. #33
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    Default Re: First build from DN Goodchild plan

    Voila the lines plan.I have cut out 5 of the ten station moulds so I think I will be going 3D soon.
    -
    Thanks for the tip with the thinner.
    -

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    Default Re: First build from DN Goodchild plan

    I cant remember the best buttock angle for planing craft,but it looks reasonable. Thats a nice fine entry too. She should be very easily driven i think. Whats the beam,about 7ft 6in? Thats a nice hull.

  35. #35
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    Default Re: First build from DN Goodchild plan

    Dimensions:
    Length over all 25 feet 0 inches
    Length waterline 24 feet 1 inch
    Beam 7 feet 3 inches
    Draft 2 feet 3 inches

    I like the lenght to beam ratio I think it will come out very nicely

    BTW Thanks for talking me in to keeping the flare now with the front 5 station moulds cut it starts looking real cool already.
    Will post some pics from the station mould cutting tomorrow.

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