Building Gigi - A 16' Outboard Runabout

[wizbang 13]

Re: Building Gigi - A 16' Outboard Runabout

You've convinced me that the transom knee needs beefing up. So, I made 3/8" ply cheeks and epoxied them on either side of the knee. Thanks for your comments, Bruce, Dave and Jeff.

[ATTACH=CONFIG]137793[/ATTACH]

it didnt need beefing up, it needed better understanding of grain orientation.
the ply will help, but the plywood grain is still 45 degrees off

[gordonscg]

Re: Building Gigi - A 16' Outboard Runabout

The boat is looking great.



I ran into the same problem using western red cedar. I've stopped using it -- even with care collecting all dust and wearing a good quality dust mask, I still get a reaction like yours. Be careful -- the allergy can only get worse. I was using the cedar to make kayaks and kayak paddles. Most any other soft wood is good enough for these applications, so I find no need to risk exposure to the red cedar.

If I was doing it again I would think hard about using something other than WRC. Besides the health hazard, it is way more expensive than other softwoods here in Minnesota. Anyway, now that my cedar is encased in epoxy and fiberglass, it shouldn't cause me any more problems.

[gordonscg]

Re: Building Gigi - A 16' Outboard Runabout

it didnt need beefing up, it needed better understanding of grain orientation.
the ply will help, but the plywood grain is still 45 degrees off

"Nothing would be done at all if you waited until you could do it so well that no one could find fault with it.” – John Henry Newman

[gordonscg]

Re: Building Gigi - A 16' Outboard Runabout

Staining and Fiberglassing the Transom

I trimmed the overhanging bottom strips at the transom and rounded them over so that when I fiberglassed the transom and overlapped the bottom, the glass would not have to go around a sharp corner.
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In anticipation of glassing the bottom, I planed a 2”-wide flat along the centerline for the keel and outer stem.
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Also in anticipation of glassing the bottom, I lined off for the first lapstrake by measuring the girth from the transition to 1" below the sheer at each station and dividing these distances by 6 since there will be 6 strakes per side. The 1" was to account the width of the rub rail at the sheer. I beveled the transition strips to match the angle for the first lapstrake and planed 12” gains at the ends of each transition strip so that the strakes, when installed, will lie flush (or nearly so) with the stem and transom.
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I sanded the transom with 120 grit, vacuumed and wiped with solvent and stained it with mahogany stain. After allowing the stain to dry for 2 days, I applied 9 oz. fiberglass cloth to the transom, using West System 207 clear hardener. I extended the fiberglass 2” up onto the bottom planking. I filled the weave of the fiberglass with 2 additional coats of epoxy and trimmed away the overhanging fiberglass.
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The next day, I sanded the fiberglass at the transom edge with 80 grit, cleaned the area with methanol and masked off the transom. I made up a peanut butter-thick blend of epoxy, microfibers and wood flour and applied it to the radiused transom/bottom edge using a putty knife to create a sharp edge. The next day, I sanded the corner flat and applied additional epoxy/wood flour to fill gaps and low spots. Finally, I unmasked the transom, sanded it and the trailing edge with 120 grit and applied another coat of unthickened epoxy.
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These steps took me about 30 hours over 2 weeks.

[wizbang 13]

Re: Building Gigi - A 16' Outboard Runabout

I'm glad to see you re sharpened that lower edge.
The radius can steal some horsepower.

[jpatrick]

Re: Building Gigi - A 16' Outboard Runabout

I'm glad to see you re sharpened that lower edge.
The radius can steal some horsepower.

How sharp does sharp have to be?

Jeff

[wizbang 13]

Re: Building Gigi - A 16' Outboard Runabout

How sharp does sharp have to be?

Jeff

Sharp and fair as you can.
It helps to pop on plane faster and adds to top end.
leggo de wata !

[gordonscg]

Re: Building Gigi - A 16' Outboard Runabout

Fiberglassing the Bottom, Attaching the Keel and Dry-Fitting the Outer Stem

I fiberglassed the bottom with 17 oz. biaxial cloth, one side at a time. I sanded the bottom along the transom edge to roughen the epoxy and then vacuumed and wiped the bottom with methanol. I masked the transom and covered the frames and molds with plastic sheeting. I applied masking tape on the port side of the bottom 3 inches from the centerline so that I could later cut a straight edge along it. I then spread the fiberglass cloth on the starboard side and trimmed it so that it overlapped the tape on the port side and the transition strip. I used strips of masking tape to hold the cloth in place and carefully smoothed the cloth over the surface.
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Starting near the center of the boat, I applied unthickened West System 105/205 epoxy to the fiberglass using a plastic squeegee to spread it and work it into the cloth. I worked from the centerline towards the transition and from the middle towards the ends of the boat. I reapplied epoxy to dry (white) areas. I had to trim away some of the cloth that overlapped the inner stem because it would not lay flat over the sharp corner. When the epoxy had partially cured, I trimmed the overhanging fiberglass along the centerline, transition strip and transom and removed the masking tape. After the epoxy had fully cured, I feathered the edge of the fiberglass along the port side of the centerline and applied a coat of Total Boat TotalFair along this edge which I later sanded smooth. I then repeated this process to fiberglass the port side.
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I roughed out the keel from the blank I had previously laminated from 2 lengths of 1" fir. I beveled the keel to a 1"-wide face and cut a scarf in the forward end where it will join with the outer stem. I cut a matching scarf on the aft end of the outer stem and temporarily attached the outer stem with #12 x 2” screws. I epoxied the keel (but not the stem) to the bottom, using temporary screws to hold it in place. The keel was slightly bowed so I used a stick from the wall to hold it straight while the epoxy cured. I also drilled a hole for and temporarily fit a bronze bow eye through the stem.
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I installed three ⅜” bronze carriage bolts through the keel, two aft through the transom knee and one forward through the aft end of the inner stem. Finally, I faired the keel-stem joint where the width of the face transitions from ¾” on the stem to 1” on the keel and flattened the bottom of the keel. These steps took me about 44 hours.

[gordonscg]

Finishing the Bottom

I filled the bottom fiberglass with two coats of epoxy thickened with West System Microlite filler and sanded again with the longboards. I filled a few remaining low spots with TotalFair and sanded them smooth and fair also.
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I sanded, filled bolt heads and epoxy-coated the keel and added epoxy filets on either side.
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Next, I rolled and tipped Pettit 4700/4701 2-Part Epoxy Primer on the bottom and keel. It didn’t go on as smoothly as I hoped so I had to sand the bottom again lightly with 80 grit.
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I installed 12 feet of 1” brass half-oval on the keel bottom using 3M 5200 and #8 x 1" screws spaced 6" apart. I later filled the screw heads with TotalFair and sanded them smooth.
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After a thorough shop clean-up, I vacuumed the bottom, masked it off and wiped it twice with methanol. I then rolled and tipped 2 coats of red Vivid antifouling paint. It covered well but dried too fast. I couldn’t keep a wet edge even after thinning as directed. It had a very strong solvent odor which I noticed after I removed my respirator. I plan to apply a 3rd coat before launch.
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These steps took me about 49 hours. Next up - the big flip.

[2dogsnight]

Very cool!

[gordonscg]

Advice Needed

If you have been following my Gigi build, I'm sure you realize by now that I am working well ahead of my postings. Well, I've run into a bit of a situation in real time and I need some (constructive) advice on whether it needs a fix and, if so, how I might go about fixing it. I have finished steam bending the ribs in place and have begun riveting them to the topside planking. The situation/problem is that in about a dozen places the ribs are up to 1/4" to 3/8" from the plank lands and I cannot force them to contact the lap -- believe me I've tried. This has happened mainly at the first lap above the transition from the strip-planked bottom (circled area in drawing). Apparently, I should have put some reverse bend in the ribs at these points when they were still bendable. Other that these dozen or so places, the ribs contact the laps nicely as they should. I've considered just installing rivets as usual in these spots and not worrying about the gaps. I've also considered installing oak shims or plastic or rubber spacers to fill the gaps but they would be somewhat visible. I would appreciate any suggestions you might have - other than removing the ribs and starting over that is! Oh, I should also mention that the laps are all epoxy-glued so the planks don't depend entirely on the rivets to hold them in place.
Thanks,
Steve
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[wizbang 13]

post #5...I tried to tell you.
just bite the bullet at this point and fill it with dukee....two pump job.

[gordonscg]

Flipping Gigi

Now that the bottom was mostly finished, it was time to flip Gigi upright so I could begin work on the interior and topsides. My plan was to build gantries like those I saw in a YouTube video at The Wooden Boat Experience: https://www.youtube.com/watch?v=CfNzSBQyDBg&list=PL8Bx3AEvTjGDdM8bN1Nx-QH4UUWdHnH7B&index=34.

I made two gantries with 4x4 posts attached to the walls of my shop and beams made from doubled 2x8s with 1/2" ply spacers across the top of the posts. I used metal brackets and OSB gussets to attach the beams to the posts. I screwed 3/4" ply hangers on either side of the beams at about the width of the boat. I installed 1/2" bolts with lengths of 1" PVC tubing between the hangers. The tubes rotated freely on the bolts and would serve as pivots for the straps used to rotate the boat. I attached a chain hoist at the center of each beam with chain wrapped over the beams. Next, I screwed longitudinal bracing to the cross spalls of all the molds and wrapped lifting straps (yellow) under the boat and up to the chain hoists.
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I rigged (blue) endless ratchet straps through the pivots on the gantries and around the boat and detached the boat from the strongback. Then, with the help of my wife and a couple of good friends, we raised Gigi off the strongback using the chain hoists and the yellow lifting straps until it was high enough to clear the floor when it was rotated. We pulled the strongback out from under the suspended boat and I removed the front, triangular portion of the strongback.
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We tightened the blue ratchet straps to take the load of the boat and loosened the yellow lifting straps. Then we slowly rotated the boat until it was upright.
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When Gigi was upright, we re-tightened the yellow lifting straps to take the weight of the boat and loosened the blue straps. We pulled the shortened strongback back under the boat and centered it. We lowered the boat onto the strongback, leveled it fore-aft and from side-to-side, placed blocking under the keel and screwed padded supports to the strongback at the turn of the bilge forward, amidship and at the transom. Lastly, I added braces from the top of the stem to the walls to firmly hold the stem vertical.
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This felt like a major milestone in building Gigi so we went out to dinner to celebrate! Including building the gantries, this work took about 27 hours. Once everything was set up, the flip itself took about an hour. I will use the gantries again when it comes time to lift Gigi onto a trailer but that won't be for awhile. Next up: Interior Work Begins.

[gordonscg]

Interior Work Begins

The first tasks after turning Gigi upright were to place three ratchet straps around the hull to hold its shape and then remove all of the temporary molds and bracing. Next, I sanded the interior bottom with 80 grit, rolled on a coat of TotalBoat Penetrating Epoxy and filled all of the screw holes and a few small gaps between planks with epoxy and wood flour.
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I dry fit 3/8" ply motorwell sides between the transom and the aft bulkhead.
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I fiberglassed the entire inside bottom with 9 oz glass but I did not add fill coats at this time. I added cleats to the back side of the aft bulkhead and used the ply cutouts to make hatch covers with some decorative ventilation. I made a similar hatch cover for the forward bulkhead and added a cleat to support the sole boards.
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This work took me about 54 hours. Next up: Floors and Other Interior Work

[gray duck]

nicely done with the flip.