Scratch-Built Hydro

[FloatDaBoat]

Boat's lookin good! Your really doing this one perfect, have you considered taking a mold from it?

This is a One-Off build, & I have no intentions of pulling a mold from the hull. In fact, the plans no longer exist in entirety, as I cut templates from the poster board paper upon which they were drawn to aid in certain areas of fabrication.

[FloatDaBoat]

Slab Sided

The remaining four bottom skins attached & rough sanded to shape … need to feather-in all the intersect joints to an imperceptible smooth transition [to the touch, not the eye] … then the glass work can begin.

[FloatDaBoat]

Primered

I Mixed-Up some laminating resin with the base coat pigment color added & brushed it on the hull bottom. This will act as a ‘Primer’, which will allow me to apply the glass cloth without first laying down any resin. This will enable me to cut the cloth to precise dimensions for areas (i.e., the flat bottom panel & the vertical sponson sections) where I only want ¼” of overlap. These overlap areas will be feathered before attaching the next adjacent section. Just need to scuff the resin with 220 grit sandpaper, lay the glass in place, then brush on the laminating resin. This process eliminates some of the sanding required to get rid of any excess glass/resin, so when the whole bottom is done, it appears to have been done with a single piece of fiberglass cloth.

With temperatures exceeding 100 degrees Fahrenheit (37.8 degrees Celsius) every day, I’m limited to doing all my glass work early in the morning while it‘s still a little cooler [to extend the resin pot life], as all my glass work is done outside.

A Glassin’ I Will Go . . . .

[FloatDaBoat]

Glass Bottomed Hull - - Base Coat

Finished applying the last two pieces of fiberglass to the Sponson ‘Inner Thighs’ at 2300 hours last night [moved indoors, despite the Wife's displeasure]. The resin was still too green this morning to edge sand properly, but I thought I’d post a progress pic anyway.

For those of you that don’t already know, the close-up photo shows how to correctly wet out fiberglass cloth - - the weave should be visible, not over saturated. Laying down too much resin only causes the cloth to ‘Float’ above the surface to which it’s intended to adhere to. Additional resin doesn’t increase the strength [actually weakens it a mite], just adds extra weight, & requires a lot of unnecessary sanding to remove it in order to achieve a nice smooth appearance.

I’ll sand this down just enough to level it, then apply a finish coat of laminating resin as thinly as possible with a finishing brush. If this were the final glass layer, I’d wet sand with no coarser than 600 grit to get a nice look, which isn’t required if one intends to paint over the surface. I’ll be applying a second layer of glass (tinted with phthalo blue transparent pigment) to get the look I want, so I’ll just smooth out the finish coat with 220 grit.

I’m so involved with this build, that I haven’t even run my scratch built cat since I started . . . .

[FloatDaBoat]

Phthalo Blued

Finished with the application of the 2nd four ounce layer of fiberglass impregnated with the Phthalo Blue transparent pigment. I found that even a few thousandths difference in thickness of the laminating resin creates contrasting areas of color tint, which produces a mottled affect. I won’t really know what the final look will be until it’s wet sanded, but that’ll come after I’ve attached the decks. I won’t affix them until after I’ve installed all the blind nuts for the Strut, Rudder, & Turn Fin brackets (which I haven’t fabricated yet, as the Stainless hardware is due to arrive via UPS this afternoon).

Sure would be nice if I had a Paint Booth, as Epoxy Resin has an enormous affinity for attracting dust while curing . . . .

[FloatDaBoat]

Oops

I discovered what actually caused the mottling of the transparent blue resin coating - - it’s steel wool residue. I had earlier cleaned the surface with denatured alcohol, then just before I applied the finishing resin, I used an old paint brush to remove any dust that may have accumulated since then (a couple of hours had passed). The brush was contaminated with steel wool residue, which was attracted by the static electric charge of the fiberglass covered hull.

The only remedies are to strip it off & redo it, or paint it, neither of which I’m going to do. I’ll just live with it, & make sure I pay closer attention in the future - - Lesson Learned !!!

Hopefully, there’s not enough steel impregnated in the resin to interfere with reception of the 2.4 Ghz XMTR signal to the RCVR.

Stuff Happens . . . .

[mhall]

This is a very interesting build and very nice looking as well. I can't wait to see what it looks like when it's done. Nice job!

[Shooter]

Float - Great glass lesson! I always wondered how it appeared to be one pc of glass. Could you go into detail with the "feathering" approach? Would very much appreciate it. I'm sure others could benefit as well.

Too bad about the steel wool. I know exactly how you feel. Messed up several paint jobs that way. Dang little curlys!

[FloatDaBoat]

Sanding Fiberglass

Float - Great glass lesson! I always wondered how it appeared to be one pc of glass. Could you go into detail with the "feathering" approach? Would very much appreciate it. I'm sure others could benefit as well.

Too bad about the steel wool. I know exactly how you feel. Messed up several paint jobs that way. Dang little curlys!

Feathering: The main areas that require fiberglass to be feathered are where two angles of ~ 90 degrees (with no curve at the transition) intersect, i.e., a sponson vertical inner side & the tunnel bottom.

To begin, the fiberglass cloth should be cut to a width with just about ¼ inch overlapping the angle. If the bottom’s 8 inches wide between the sponsons, cut the cloth 8 ½ inches so that a quarter inch will ride up the sponson vertical surface on either side. A very high quality pair of scissors is required (don’t use scissors with serrated cutting edges), as you don’t want the weave of the fiberglass to unravel. Also, if you use those same scissors to cut something like masking tape, be sure to clean them with a solvent to remove any residual tape adhesive, as this will grab the glass strands & cause them to unravel, also. Once cut to size, handle the cloth carefully.

Epoxy the fiberglass using laminating resin applied with a good finishing brush, once again being careful not to unravel the cloth edges. Don’t apply too much resin, which causes the glass to float. But, make sure the glass is fully wetted. Any weave that’s not completely covered will be, once the finish coat of resin is applied. Don’t attempt to do the bottom & sponson sides at the same time, as that’s a disaster waiting to happen.

To get the best sanding results, it’s better to wait 24 hours to ensure the resin has hardened well. I start with a piece of already worn 100 grit aluminum oxide paper, taped to a sanding block made of a half inch thick piece of plywood that’s an inch & three quarters wide. The block should be long enough to fit in the hand comfortably. Make sure the paper is cut with about an eighth of an inch extending past the end of the block, as this allows a softer ’feathering’ touch. Also, wrap the paper around the sides of the block, as this prevents tearing of the paper‘s edges.

Careful sand the exposed edge of the glass that extends up the sponson side, avoiding cutting into the underlying surface of the sponson. You should be able to observe individual strands of glass beginning to taper along the edge. Run a finger over the edge to judge the amount of glass & resin remaining. Once it starts to feel smooth, switch to a finer grade of sandpaper, & continue the process until the edge ‘disappears’.

This is the point at which I switch to “Old Faithful”, a sanding block made from a quarter inch thick piece of rubber floor matting (identified with an asterisk in the attached photo, along with some of the other sanding paraphernalia used on this build), that works superbly for this purpose.

Next, apply fiberglass to the sponson sides in the same manner as the bottom. Repeat this process until all surfaces are covered.

To get a nice smooth final surface, apply a thin coat of finishing resin to the entire hull after it‘s been cleaned & lightly sanded to roughen-up the surface [which allows the finish coat something to glom onto]. This will fill in any weave left exposed in the glass during the initial application, which was caused by gravity doing it’s job while the laminating resin was still in a low viscosity state. This would be less troublesome if it were possible to apply the cloth & resin to a perfectly level surface.

Carefully wet sand the finish resin coat with no coarser than 600 grit. No sanding blocks here. Cut two pieces of paper twice the size you want to work with, fold them in half with the grit facing outwards, then insert one inside the other (end result is four individual sanding surfaces, which are easily rotated to utilize the level of wear of each paper surface as desired/required). Avoid sanding into the glass weave. Use lots of water, but dry the surface often, as you won’t know if you’re getting into the glass cloth while it’s still wet.

Have patience, & you’ll end up with a nice finish - - with Lots O Luck !!!.

Clear as MUDDY water ???

[FloatDaBoat]

This is a very interesting build and very nice looking as well. I can't wait to see what it looks like when it's done. Nice job!

Thanks, but it seems the further along I get, the more obstacles I have to hurdle. Most of the mistakes made will only be known to myself - - HAW !!!

It's always a struggle . . . .

[Shooter]

Thanks a ton for sharing your fiberglass expertise!!! I can tell the time you have into it.

The older I get, the more I realize the time it takes to do good work. Take your initial guess, then double it, and then add 5 hours. That's pretty much my new time estimate strategy......

Another equivalent is wife's estimate multiplied by 32. (i.e. "when are you going to build a built in bookshelf??? It only would take a couple hours!)

[FloatDaBoat]

Turn Fin Assy

I haven’t done much work on the Hydro lately, as I’ve been busy re-doing some wooden Dallas Cowboy Placards for an old Army Buddy [since 1976], who’s in the Mother of All Battles with Neuro-Endocrine Cancer right now.

I did manage to squeeze in enough time to fabricate the Turn Fin Assy. I’ve used gasket sealer to bond a piece of 240 grit wet sandpaper to the face of the disk on the fin bracket (no pic yet), which will act as a clutch plate in conjunction with the other disk on the mount that attaches to the rear of the right sponson. This will allow adjustment of the fin angle. I still have to shape & sharpen the fin itself, but the T-nut (also known as a Nut Insert , Blind Nut, Whatever) mount has been epoxied inside the sponson. I sealed the mount with a piece of fiberglass plate to prevent water from entering the hull through the bolt/T-nut threads.

Pics . . . .

[FloatDaBoat]

Thanks a ton for sharing your fiberglass expertise!!! I can tell the time you have into it.

I know a little bit about a lot of things … but not a lot about any one thing … I’m no Expert on anything; I’m willing to share what little knowledge I possess.

Knowledge is Relative . . . .

[FloatDaBoat]

Tubes & Foam

Pic #1: Water cooling supply tube, installed with a solder splice to reduce the size of the holes required through the hull.

Pic #2: Water pick-up attached to through hull supply tube (one on each sponson). An L-shaped spray rail will mount just above the pick-up opening to force water into the system. I’ll move the pick-ups an additional half inch or so higher by re-drilling the mounting holes in the brackets, as this was a test to determine exactly how much space was available for the silicone tubing to be attached without kinking it.

Pic #3: Great Stuff foam flotation added. All the spaces between the sponson frame members will be autonomous air tight chambers once the decks are attached - - some insurance in case any of these areas become punctured, which could happen due to a massive catastrophic event [like crashing into the rock wall {at 300 MPH … HAW !!!} that surrounds the lake I run on].

[Fluid]

I'm concerned that your water pickup will not get sufficient water. It will be well above any spray generated from the sponson while running straight ahead on plane. It may grab some water in corners and waves that wash by in rough water, but it will not obtain a steady supply. Moving the pickup higher will only make it worse. You want a steady water supply, not one full of air - which does a poor job of cooling. Why not use a proven, more conventional pickup, or extend the one you have below the sponson transom bottom?



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