EBB's PHOTO GALLERY THREAD

[c_amos]

Ebb,

Just read through this thread again, looking at your hatch-mounting-frame-building methods. Think my Bomar hatch will stay in it's box for a while longer.....


Would love to see an update of your progress.

Thanks,

[ebb]

Really not so difficult. There must be 10 ways to do it.
Why not put the question out on a new thread to get some
responses not related to this thread. Mike Goodwin, Frank
Durant, for instance, probably know and recommend a far simpler
method than what ebb came up with. You betcha.

What's Tony G. up to these days???

OK, snake with legs here:
It's been awhile since those Bomars (pg 10 136-7-8) were messed with, and they are not even bolted in yet!
Believe I had to cut the old hatch coaming off - without making the hole larger, and grinded it fair to the camber. Then laid out the larger hole my Bomar required. I knew what wood I had to use for the 'lining' (coaming?) for the Bomar and cut a hole that the wood would line up with on the inside of the Bomar flange. Made sure I cut the hole square by adjusting the foot of the jigsaw (or bluetape on a stirring stick). The liner is essentially a 90 degree box in the hole. So you can temp screw the box together. Ground off the gelcoat out a couple inches all round.

Decided on a minor forward tilt. Slightly higher on the aft side. Don't know why. If you cut the liner tight enough (force fit) just lay the Bomar (took the top off) on the pieces and tap them til you're satisfied, parallel with the deck, tilted, whatever. Doublesided carpet tape may work too. Can also hold the liner (box or pieces) by screwing into the balsacore, but you'd have to make these holes disappear later.

Cut the bottom of the liner to close to the finished depth and forward curve and aft curve (they are different.) Use a suitably sized little block of wood (width of proposed trim) or a compass to scribe. It would help if you have a finished smooth surface on the roof inside.

The Bomar flange is 1 1/2" wide. The liner in 338 is 1/2". That allows ample solid material for the bolts that fasten the hatch (the filler is 1" wide) - bolts go round the outside of the flange about 1/2" in. The material in the photos is 3/4" thick. With that thickness it's obvious I intended to recess the nuts. If the result is too 'busy', a thin finishing strip might go over them. Or some resilient peel and stick rubber. Could let the liner run proud and fit in thinner trim for the bolts. That way there may be some protection for the top of the head.

The trim around the hole will take some fitting and as an option be held in place with screws thru the liner into the edges if thick enough. Small screws were used as the plugs are are only 1/4". This is the trim that the bolts from the Bomar will come thru. The trim will then be held quite securely! You will have to make a paper pattern to create radius trim pieces on a bandsaw out of thicker stock for the foward and aft. An oscillating drum sander is very helpful too. Would do it that way (skinny trim) if I did it again because it would help the hatch look smaller and more tidy and create a couple pleasing shadow lines. But you don't have to do this til later. Or, you can finish off the inside pieces up to the final sanding. depending on your bedding choice, you can positively support the trim pieces without screws with spring battens from the V-berth or sole. Until you are ready for bedding compound and final Bomar instal.)

You have to prepare and sand the liner to its finished shape. Because you won't be able to remove it after the next stage. No reason that whole hatch support couldn't be wood. However if you decide on an all wood frame under the Bomar it probably would have to be taller off the deck. The unconventional way described here gets the hatch as close to the deck as possible. The fronts of the Bomars sit on the deck.

Now, a perhaps controversial 'cheat'. Blue tape off the narrow outside edges of the Bomar bottom frame very very carefully. But befor that apply 2sided fiberglass carpet tape to its bottom - trace & cut it with the utility blade to the exact outside profile leaving the peeler strip on (epoxy doesn't stick to it - however mylar is a better, smoother, flatter release surface and it is recommend here.) Place it taped up right on the liner. Center the inside edges on the liner. Now's the time to get the liner flat and square if you need to (low angle plane.) Then firmly clamp the prepared frame to the liner.

Fill the space under the frame with mishmash.
Make sure the wood in there is juiced and primed and load in a mix of cabosil, glass fibers and epoxy. But don't fill quite all the way out to the edge {'the edge' means your edge, ie you might want to lean it way out on the bottom...] at the bottom! After this is set you can take your form off (the Bomar bottom frame) and check how well you did. But you don't HAVE to move it yet, ok? Might be better to leave it alone, because you may have to mask it over again.
Fill any voids (can be done later). Make sure your wood to epoxy joint is seamless. You hopefully have great confidence in the epoxy you use! No leaks will happen at this join! You are molding and bonding to the deck. And that part of the liner that sticks up out of hole. [Because the wood can expand and contract on all its other sides the epoxy/wood joint should never open up imho. In the final install you will be bedding the frame in polysulfide (no doubt) and the fastenings are going thru the epoxy buildup - SO the wood is under no stress!!!]

Clamp the frame back in place and fill out to the edge with filleting mix (epoxy and fumed silica.)* Always prime the surface first with plain epoxy and blot or wipe away the excess. Add universal color (white, like gelcoat, is good) if you wish. Here you decide how to hold your spatula blade. I like a little splay outward to this riser. A steady hand. The rounded corners are a butch. But once it's set, take off the form again and with clothbacked sandpaper carpet-taped to a piece of plywood sand away until the slope and surface are pretty smooth and shapely. Mostly. This filleting stuff can get pretty hard. Keep the deck surround pristine as well. This way you can shape to your heart's content and your muscle's burn. Get those corners all the same (you can slice with a sharp chisel if the plastic's not totally set) even if the slope is not quite like the straight runs. You're 'trueing' up the hardened goop for the next ( easier) stage:

Clamp the rig back on and fill and shape with easy sanding fairing mix. (WS 407 and laminating epoxy.) The smoother the surface is - and thinner the last passes of fairing compound are - the more finesse you gain.

[Have since, on 338, filleted (rounded) the join at the deck you see in the photo and botched it - but with fairing mix its easy to sand and shape till it's smooth and even. A piece of sandpaper around a dowel is perfect here.]



__________________________________________________ ______________________________
* FILLETING MIX -when you mix 2-part epoxy and fumed silica together you get a kind of gel.
You experiment to find out how stiff or loose is good for you. When you prime your work with plain 2-part liquid you create the bond to the surface you form the gel to. I brush the liquid on with a brush then blot and wipe the surface 'dry' with paper towels.
If you don't the liquid left behind will combine with your gel and change its consistency, making it looser. It then can sag and fall out of the shape you want. Filleting mix is structural. Gets very hard and difficult to remove material from when shaping after it's set.

FAIRING MIX - is your laminating epoxy mixed with West System's 407 powder. It will become a paste. It becomes a hard but relatively easy material to sand. It's the brown stuff 338 has all over the outside of the topsides in the photos. It becomes a hard surface that can be feathered thin and sands easy. That is why in building up this pad under the Bomar frame you want to leave sanding room so you can fair it even and smooth.

MISHMASH (not my word) is 2-part mixed with chopped fiberglass and fumed silica. It is structural and is a void filler. It is hairy and hard when set, horrible to grind and sand. The proportions you experiment with, but you don't mix in too much glass. It's there to keep the mass from becoming too brittle, muscle fiber. In the above deck build up, you tuck it in under the taped frame to avoid dealing with it again!!!
Sure hope some of this makes sense......

[c_amos]

I have read it three time now, and I think it is getting more clear. Sounds like being a master epoxy craftsman makes this easier... That is ok, I have got plenty of sandpaper.


Thanks for the break down Ebb, I'll be sure to post the results when I di it.

[Bill]

Just finished a photo shoot at Ebb's boat and found this example of "encapsulated" lead ballast lying next to his boat . . . At first I thought he might have started a new project . . .

[Bill]

Ebb replies: "Bill, you don't know this: but I removed the ballast from 338 to make up for all the weight I've added up top."

[Bill]

Ebb: "Showing the end on the new toerail and a transom begging for a taffrail!"

[Bill]

Ebb: "Curtains and runs from a disastrous spray-on primer fiasco. Expectations were of a thin easy to sand final prime. Even paid the guy for his time. And yours truly spent the hottest days on record in San Rafael longboarding and sanding the damn stuff nearly all off!"