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  1. #1
    Join Date
    Dec 2015
    Location
    Waco, Texas
    Posts
    3

    Default GIS - Some random beginner questions

    I've just downloaded the GIS plans and intend to begin a build later this spring after my wife and I relocate our family to the Vancouver WA area. A house with an appropriate-sized garage/shop is already in our house hunting criteria. I've done a good bit of woodworking and finish carpentry over the years so have most if not all the required tools but this will be the first boat.

    In any event, after spending hours reading through forum posts and examining the plans I do have a number of questions that I haven't seen answered anywhere.

    1. Kits vs scratch. I see several shops offer kits in the US including one in Portland. I'm inclined to go the kit route but am wondering how polished the kits are. Are the goat kits sold in the US CNC machine cut to perfect tolerances like say the Chesapeake Light Craft kits? or the kits just hand lofted and cut same as an amateur might do it and require some finishing and fairing.

    2. Transom cutouts for motor mounts. I have seen various goat photos that show a transom cutout for a motor mount but nothing about this in the plans. I will definitely be mounting a small outboard at some point. I am wondering if there is an established dimension for this cutout and if the transom is otherwise the same, or if the entire transom is reshaped. Also, what is the appropriate gauge and type of metal to use for the motor mount. I have seen various different examples on the internet. Does it make a difference depending on the intended motor or is there an appropriate standard cutout size and position that works best?

    3. Spacered inwales. Most of the builds I have seen have square inwale spacers. This is what the plans show. But I have seen some on other boats that are half-round cove shaped to produce gently rounded spacer gaps. To my eye this looks better. I have a Bosch router and router table and I imagine it would be relatively simple to set up a jig to cut half-round shapes out of all the inwale spacers. Is this how one does it? Any advice or complications involved with doing this sort of modification?

    4. Bow eye. The boat will spend most of its life sitting on a trailer so I'll likely want to be mounting a bow eye for lashing the boat to the trailer. I see no mention of this in the plans. Is there any advice on the correct size, position and stage in construction for mounting a bow eye?

    I'm sure I'll come up with a million more questions as this project proceeds, but those are the first ones that come to mind. Thanks guys.

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  3. #2
    Join Date
    Feb 2008
    Location
    Eustis, FL, USA
    Posts
    2,270

    Default

    Welcome aboard.

    The GIS, like many small home built boats, is subject to much interpretation. This is good, assuming you don't move major elements around too much. Things like outboard brackets or cutouts, bow eyes, inwale spacer detailing, etc. are really up to you, as it's likely you're not going to affect the design sufficiently enough to screw up her balance.

    I too like "coved" spacers, which also tend to save a smiggen of weight and relieve stress risers too. The spacers can be as fancy or plain as you wish. You're the boat builder and these types of decisions will occur repeatedly, throughout the build. In fact, this is what boat building is all about - problem solving and "engineering on the fly". There'll be lots of decisions to contemplate, with some approaches proven and accepted, while others, relatively unknown, because you're one of the few that thought of it. This is what makes each build a unique thing.

    Yes, there are specific recommendations for outboard cutouts and splash wells. These are engine size dependant of course, but generally, given you only need a rubber band and a prop to push one of these puppies, the smallest well/cutout is desirable.

    If you have questions about the kits available, give the guy a call. They'll give you the scoop, maybe with a little fluff to keep you interested, but as a rule, the CNC kits are fairly precise, once a prototype has been worked through. Will you need to make some fits, yep you're darn right, welcome to boat building, but as a rule the CNC stuff is as precise as you can ask for. Personally, I like to cut my own, mostly because I usually make enough changes to the design, that a lot of waste will occur in a kit.

    As to a bow eye, well you'll install this when you have access to the completed stem. Mount it as low as practical, so loading and launching is easier, so long as it's clear of the water, you'll be fine. You could wait until the boat was completely finish, then drill for the eye, but most plan for it during assembly. I've put them in boats where none previously existed, simply drilling an appropriate diameter hole, filling with goo, redrilling the goo filled hole for the shank of the eye and bingo, a bow eye. A GIS needs not much for an eye, but too small makes trying to use it a pain in the butt, so look at 3/8" (bolt diameter) as the smallest "serviceable" eye.

  4. #3
    Join Date
    Dec 2015
    Location
    Waco, Texas
    Posts
    3

    Default

    Thanks

    It is most likely that I would acquire the engine after the boat is constructed, not before. I'm guessing something like a 2.5HP Yamaha or the equivalent. I don't have any motor ready to go. I'll probably keep an eye on Craigslist for a while before springing for something new. The Yamaha manual specifies that the correct mounting position is with the lower cavitation plate between the bottom of the boat and 1" below the bottom of the boat so I'll probably have to go to a dealer and measure out an outboard in person to determine how much of a cutout is appropriate. Hopefully these small outboards are fairly standard size so a cutout for one brand will work with others. I just want to have the boat built up ready for an outboard from the start as it seems easier to design the transom properly from the beginning rather than retrofit. According to the instructions in the plans there is the suggestion to build a reinforced mounting block in the center line above the rudder mounts but this would make switching between motor and sail a more complicated process and require storing the motor inside the boat when not in use. Not something I really want to do. But I guess it is the correct way to do it if the boat will be used long periods under power as the outboard should be more efficient when in line with the keel of the boat.

    As for cutting one's own plywood. What is the preferred method of doing this at home? I own a good table saw and a good DeWalt circular saw and a good Bosch router. I don't have any decent hand saws or a band saw. I'm not adverse to buying more tools. I have read about people using circular saws with fine tooth blades cutting very shallow. Also people using Japanese hand saws. I have a cheap saber saw that is useless for fine work but will work to rough things out. And what is the preferred method for finishing plywood edges?

  5. #4
    Join Date
    Jul 2012
    Location
    Santa Cruz La Laguna
    Posts
    134

    Default

    Some info for you:

    Mik has some info at the beginning of his plans regarding tools required. His suggestion for cutting out the plywood panels is to use a jigsaw. This is what I used and it worked well. Cut a few mm outside the lines with the jigsaw and use a hand plane to get down to the lines. I also bought two Japanese pull saws, an orbital sander and a small edge plane. I did end up using a router for a few small things also.

    Regarding the inwale spacers, I used a friends drill press and we made up a small jig and used (I think) a spade bit. Simon, who in my opinion has produced one of the nicer boats on the forum, used a router and described what he did here.

    Good luck with your build, I look forward to following it.

  6. #5
    Join Date
    Sep 2011
    Location
    Gothenburg, Sweden
    Posts
    100

    Default

    I cut out my panels with a japanese pull saw, as I enjoy working with hand tools. Trim to the line with a hand plane as surlyone says. For an outboard I think that you have the right idea with the 2.5hp one. All my sailboats with an outboard have had the engine mounted to one side of the transom, it really doesn't make that much of a performance difference and is much less of an hassle than having to unhook the rudder and mounting the engine everytime you want to use it. If you have a long shaft motor you don't need much of a cut out, but with a standard one you will need to cut out a bit. Mik says the transom will take a small outboard without any re-inforcement, but if you make a deep cut out you'd better add some wood to compensate. Have a look at what other people have done and copy the solution you think look pretty. Can I also suggest that you join the Goat Island Skiff Facebook group if you haven't already done so? Yes Fb is quite evil, but there is 660 members in the group and many of them are very active (including Mik) so you'll get more answers to your questions and increase the possibility to connect with some GIS sailors in your area. Good luck with your build!

  7. #6
    Join Date
    Mar 2010
    Location
    Queenstown New Zealand
    Posts
    382

    Default

    I cut panels with a Japanese hand saw. They cut an accurate 0.5 mm kerf, it's easy to cut a fair curve, so I cut right on the line, no planing or sanding required. Quicker than the jigsaw followed by planing / sanding. I do use the jigsaw for more complex curves such as cross frames for SOF kayaks.

    You can fit a cut-out for a small outboard in the side of the transom, but the transom is quite narrow so there isn't much space. I have a 2Hp 2 stroke yamaha, presumably the smallest possible modern outboard, it needed quite a deep cut out, there isn't room to have it on the transom at the same time as the rudder /tiller are in place so I can't go sailing with the motor on the transom, it's either go motoring or go sailing.

    Ian

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