How to build a seakayak / PART SEVEN

How to build a seakayak /PART 7

Seventh part of our tutorial on how to build a seakayak Bette 500 HV, using plywood and epoxy resin , with the so called “stitch and glue” system

 

working on the hull

time required :

  • internal stiffening with glass fabric strips : 3 hours
  • external stiffening with glass fabric patch : 3 hours
  • sanding the outside of the hull: 2 hours

we left the hull with a layer of liquid resin on the inner side, now we have to stiffen the joints among panels with glass fabric’s strips ; we’ll start cutting our glass clipping into 5cm wide strips, about 50-70 cm long; then we’ll proceed with a fast sanding on the inner side of the hull, just enough to clean any drop of resin that can disturb us when we’ll laminate the glass;

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now we’ll give a first liquid resin layer on the joint and then we’ll push the glass strip on it, laying it down precisely with the gloves, letting it soak completely with resin ’till it became transparent; if needed we’ll add some resin to soak the strips completely, but just the minimum amount required

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this is the glass strip simply pushed on the liquid rsin; now we need a little bit more of resin to soak it completely

glass fabric vs. glass tape: I found that glass fabric is very much easier to soak and work than glass tape, wich is harder to soak and “drink” a little bit more resin; so I’d go for 100% fabric in my next works, the only drawback is that you have to be quite careful handling it, since it tends to loose glass wires from the warp

We’ll do this operation for all the joints among panels on the inner side of the hull, you may work dividing the hull in 5 zones (take the 4  bulkheads as reference) , complete each zone before passing to the next one, spread with the roll each drop of resin, work slowly and with care, overlap slightly the glass strips on the edges; I choose to work with quite short strips since it’s faster and easier to work neatly and clean;  working with very long strips requires a good experience or it will became a total mess of wrapped glass fabrics strips and resin;

joints hull-bulkheads: I cover with a layer of glass clippings even this joints, at least in all the low part of the hull

how much resin mix ? I worked with 120-150 ml of resin each time , then I mixed another cup of resin and so on; if you end the works with some resin just mixed, add silica and microfibers and drip it on the bow and the stern to stiffen the liquid joinery.

Laminating the glass fabric on the external side of the hull;

It’s a quite long operation that can’t be split , so keep 3 hours or more to do all in one shot; we cut a big diamond shaped patch of glass fabric some episodes ago; now it’s time to laminate it on the hull.

It’s a little bit delicate phase, buth with our trusty slow hardener for epoxy we have all the time we need to do everything without hurring too much;

we’ll start with a cental strip of glass fabric , 10 cm wide, wich goes on the centerlne form bow to stern; this will improve chafe resistance for hard landings; simply soak it with resin as we’ve just learned working inside the hull

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then we’ll start giving a layer of liquid resin on half of the hull (you may start form stern or bow, it’s the same), then we’ll take our rolled patch of glass and we’ll start to unroll it on the wet hull :check that you start rolling the patch on the right edge, bow or stern, align the center of the patch with the centerline of the hull (we did small dots with our marker to have a reference, do you remember ?) and start rolling on the glass fabric wih the paint roller to spread the fabric withou adding resin, trying to stretch it as much as you can (you may work the fabric pushing it with your hand open to stretch it ), we’ll stretch it rolling energically woth our roller starting from the centerline and going down on the sides to eliminate any bubble or wrinkle, in this phase we’re working just with the liquid resin underneath the fabric, until this is perfectly strechted on the hull; the patch will be perfect on the bottom panels, while it can do some big wrinkels on the knee panels; don’t worry, it’s normal, just take the scissors and do some vertical cuts on the glass to adjust the wrinkles doing small overlaps on the knee panels;

if you realize that you’ve not stretched the fabric enough don’t worry, simply raise it from the hull and replace it properly, and strecht it again with your hands, i had this problem on the last third of the hull;

when we’ll reach half of the hull we’ll wet with resin the remaining half and unroll the glass fabric on it, streching it it with paint roll and gloved hands and so on, keeping an eye that our dots stay always aligned withe the centerline; when you’ll have stretched all the patch properly on the hull, you’ve done the most diffcult part of the job; al that remains to do is to soak the glass with the right amount of liquid resin with you roll and cut perfectly the glass patch on the stern and bow, paying attention to eliminate air bubbles trapped under the fabric and wrinkles; at the endo of this operation take a sharp knife and cut any glass wire that has “escaped” form the warp and throw it away .

When the resin has set a quick pass of sandpaper by hand will fair any imperfection.

p.s: I’m sorry I have no pictures of this very last operation 🙁 🙁