K2FS18

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K2FS18
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Re: K2FS18

Post by K2FS18 » Mon Mar 06, 2017 9:52 am

BB Sig, those are where I used screws to hold the decks down. The decks have been leaning against the wall for too long and took a curve. When I dry fitted, I determined where I needed something to hold the decks down. I tried not to use too many. The circles are just a visual to the placement of the screw. This process of glueing down moves pretty fast for a one man crew, did not want to have to think too much.



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Re: K2FS18

Post by BB Sig » Mon Mar 06, 2017 10:44 am

As a one man show, I will be using that trick myself except, for now, most of my ply is still straight. I am going to have to add another layer of biax to the interior bottom of the hull. I am sure it will be leaning in the garage until that gets done... :(

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Re: K2FS18

Post by K2FS18 » Thu Mar 09, 2017 9:36 pm

Got the decks cleaned up and trim even with the rub rail; she is all done gluing up! so by installing the decks on top of the sides, the overall height of the rub rail increases the thickness of the decks plus the gap under the outer edge of the rub rail. No biggy until the deck goes from sitting on top of sides to nesting inside along the bow where the sides extend higher than the deck. That transition point was nasty. It went from say 2.5" to 2" within 6" and looked odd. I spent the last couple nights building that rub rail up with flour epoxy to taper that transition to about 40".Image
The photo does not show it very well. This is post flour epoxy.

Image
This photo shows the added thickness to the rub rail.

K2FS18
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Re: K2FS18

Post by K2FS18 » Thu Mar 09, 2017 9:43 pm

One other thing, that bad ass tape and paper job that was under the decks. Totally sucked getting that out. Some of it will just live under the decks for the rest of its time. The problem was, there is just not that much room to work with on the underside with all the conduits and rod tubes. I should have used blue tape and just stuck enough tape to the boat to hold and stuck the entire amount remaining to the paper. What happened was that any tape that was not stuck to something before became stuck once I started trying to get it loose, then all started to rip and sticking where I could not get my hands or tools.

Lesson learned.

K2FS18
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Re: K2FS18

Post by K2FS18 » Tue Mar 14, 2017 5:06 pm

Got the 4 oz down and slightly sanded. I used peel ply so the layup is real smooth. The sanding helps find the little areas that did not adhere well so that they can be cut out and touched up. It was really cold (or cold for us) when I glassed so I had a few more areas than I expected. First coat of epoxy with graphite; or I should say graphite with epoxy, on the rub rails and radiused edges. It was a little thick, we will see how well it sticks.
Image

Also started on the shop drawings for the trailer. Full scale shop drawings.Image

Since I have not ever built a boat trailer, and there is a lack on designs online, I figure it best to full scale to make sure it "looks" like it will work. Doubt I will save much be building myself, but at this point, it feels pretty good to have built everything possible for this build.

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Re: K2FS18

Post by K2FS18 » Tue Mar 14, 2017 5:13 pm

Found the balance point the other day as well. It is 94.5" from the transom (bottom edge). Slightly more forward than original design. That includes the empty fuel tank and small battery up front (no motor, bilge pump or micro pole at this point). I will weigh as soon as I can find a few scales. I plan on lifting it up from the roof trusses with 2 hanging scales on rear and 1 up front. Add all three weights together to get total. Should work.?. Once the weight is determined, I think I can add the other to be added weights to get the total unloaded weight and new balance point and draft depth.?.

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Re: K2FS18

Post by TomW1 » Tue Mar 14, 2017 11:59 pm

K2FS18 wrote:
Tue Mar 14, 2017 5:13 pm
Found the balance point the other day as well. It is 94.5" from the transom (bottom edge). Slightly more forward than original design. That includes the empty fuel tank and small battery up front (no motor, bilge pump or micro pole at this point). I will weigh as soon as I can find a few scales. I plan on lifting it up from the roof trusses with 2 hanging scales on rear and 1 up front. Add all three weights together to get total. Should work.?. Once the weight is determined, I think I can add the other to be added weights to get the total unloaded weight and new balance point and draft depth.?.
The balance point should be adjusted for the Longitudinal Center of Gravity which is measured at Transom on the Designed Waterline. This is where all weights should be adjusted for. That is why there is no reason to determine the balance point. A spread sheet works great as Jacques and I discussed many years ago, he now uses a computer program. This goes hand in hand with your weight. How much resin did you use the normal, then the boat will weigh what is in the study plans, are you a first time builder then you probably used more of every thing. Then use the LGC to calculate your other weights. A battery 40 lbs. 7' forward of LGC is 280. A gas 6 gallon gas tank in the stern is 36lbs x 6' or -216.

If you go to the study plans you will find all the information you need except the LCG which Jacques will give you if you ask. Take a look at the PDF file. It shows Draft at DWL 4", hull weight 240lbs, displacement at DWL 1100lbs and PPI of 280lbs. When Jacques calculates displacement at DWL he includes the motor and essential wiring and controls. Use the LCG calculation I showed above to keep things balanced as you add things to your boat.

Have enjoyed watching your build. :D
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses.

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Re: K2FS18

Post by jacquesmm » Wed Mar 15, 2017 11:12 am

Don't overthink.

You can calculate those centers to the 5th decimal but when you move your feet or tackle box, it will change everything.

You should keep weights in mind and not to go to any extreme weight distribution but plain common sense if enough.
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K2FS18
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Re: K2FS18

Post by K2FS18 » Wed Mar 15, 2017 8:00 pm

Thanks Tom and Jacques.

Before I saw ya'lls post I went ahead and weighed boat and drew the diagram below.
Image

I lifted the boat on three hanging scales and added the three weights, 508 pounds. this is with all permanent items installed, minus the final fair, prime paint on decks and sole. just a litter over design weight.

If I go with the new yamaha F25 it is 126lbs for basic model, plus 7.5lbs for the micro pole and about 60lbs of fuel when pretty much full. Giving a total boat weight w/o gear and people at 701.5lbs or so. Add two dudes and some gear, beat we add another 450.

Not sure what if any info the above drawing provides, other than being able to figure out the load on the trailer and balance point to get a good idea of axle placement. This will take me a few minutes to figure out.

K2FS18
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Re: K2FS18

Post by K2FS18 » Wed Mar 15, 2017 8:08 pm

So if I was to use a 20hp Suzuki at 100lbs verses the Yammi F25 at 126lbs, what would this do to draft?

The math involved in the post above may have to wait until I can put the thinking cap on.

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