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[FishStretcher]

The compression columns need to be much smaller than the washer inside the hull. Otherwise the outboard is only held in by the shear strength of the secondary bond from the column to core. I would suggest having fibers run transverse to the bolt axis. Or put in a load spreader like c channel. At which point, the pressure drops to the point of not needing compression columns. I think?

[FLexpat]

Originally Posted by FishStretcher

The compression columns need to be much smaller than the washer inside the hull. Otherwise the outboard is only held in by the shear strength of the secondary bond from the column to core.

Absolutely right if the columns get put in after the core is laid up - if you put columns in after the core gets laid up then you need to make sure not to drill through the exterior skin and also make them smaller in OD than your washers on the inside. If you are going down that route you can also use fiberglass washers or plate glassed in on the inside (if there is enough room) and still keep larger diameter columns. You would still need the metal washers though.

[FishStretcher]

Originally Posted by FLexpat

Absolutely right if the columns get put in after the core is laid up - if you put columns in after the core gets laid up then you need to make sure not to drill through the exterior skin and also make them smaller in OD than your washers on the inside. If you are going down that route you can also use fiberglass washers or plate glassed in on the inside (if there is enough room) and still keep larger diameter columns. You would still need the metal washers though.

I think you are right about embedded columns of fiberglas/garolite, although the transition from column oriented fibers to in plane might be interesting to think about. I am a fan of a channel as a washer to spread the load under the less stiff glass and core.

[flyingfrizzle]

I'm a big fan of using aluminum channel or flat bar to spread load too. I usually use 2 pieces of 4"×3/8" anodised flat bar between 12-20" long across top 2 and bottom 2 bolts.

[kiwi]

All good ideas. Thanks

[kiwi]

Drilled motor mount holes and drain holes in the transom, and treated the holes with thinned resin. Rolled on some Interlux Interprotect primer, sanded down, applied some more on the remainder. This stuff works pretty well at filling in some of the smaller pits that remained in the fairing.

[kiwi]

Just tried to roll and tip first coat of Interlux epoxy primer, and made a cat's ass out of it. It seems like the paint did not flow at all, and dried way too quickly. I thinned it about 25%, which is what data sheets recommended as a minimum thinning.

Anyone familiar with this paint application method, and got any tips? Does it sound like the paint was not thinned enough?

[strick]

Primers usually have a fast drying time and are very thick . Better off spraying primer.

Originally Posted by kiwi

Drilled motor mount holes and drain holes in the transom, and treated the holes with thinned resin.

Did you use epoxy resin or polyester resin? if you used regular polyester I would put a coat of epoxy over that as it seals the wood better then the former....

Love my little sceptre and yours is coming along nicely!

strick

[flyingfrizzle]

Originally Posted by kiwi

Just tried to roll and tip first coat of Interlux epoxy primer, and made a cat's ass out of it. It seems like the paint did not flow at all, and dried way too quickly. I thinned it about 25%, which is what data sheets recommended as a minimum thinning.

Anyone familiar with this paint application method, and got any tips? Does it sound like the paint was not thinned enough?

I use a lot of interlux products, It is what my local marine supplier stocks plus I really like their products. I know I usually spray my primer as well but you could roll and tip it. You need to make sure you use the right reducer. If using interlux reducers with their products they have fast drying for spraying and slow for rolling and then they have a type for roll and tip applications.

I would try the the 333 or 433 if compatable for one part paints. If you are using a two part paint you need the 2333n or 2316n reducers. It says on can what type to use.

From their site:

216 Special Thinner is a fast evaporating solvent which, when added to specified paint coatings, improves drying in cold climates and facilitates spray application. Also recommended for removing sanding residue from hull bottoms, wiping down bare aluminum clean and for the general clean-up of paint equipment.



333 Brushing Liquid is a slow drying solvent to ease brushing and facilitate the flow of specified paint coatings. Extends drying in hot weather.
Also recommended in various topside systems for removing sanding residue from fiberglass and wood surfaces.



Brush-Ease 433 is a slow drying solvent to ease brushing and rolling and to improve flow.
Interlux Brush-Ease 433 should only be used in products where it is specified in the directions, mostly antifouling paints, it is not an all purpose solvent.



Reducing Solvent 2316N is a fast evaporating solvent to be used in specific two-part polyurethane and epoxy products when spraying and is a fast drying reducer. Refer to the specific product directions for the amount of Interlux Reducing Solvent 2316N to be used.

Reducing Solvent 2333N is a slow evaporating solvent to be sued in specific two-part polyurethane and epoxy products when brushing and slow drying reducer. Refer to the specific product directions for the amount of Special Solvent Reducer to add.

[kiwi]

Strick, FF- Thanks for the tips. I did not have epoxy resin on hand so I used the polyester to coat the wood in the drilled holes. I painted some Interprotect in them also, so hopefully that'll help. I know, not optimal, but it's done. I sprayed the last time I worked on this boat, and thought I'd try the brush method for kicks.

FF- I used the 2333N reducer that the data sheet specs out for brushing. Lots of contradicting advice out there. The data sheet says to thin 25% minimum. Yachtpaint videos on youtube say to thin no more than 10%. Anyway, I think I thinned the first coat too much.

I sanded most of the brush strokes out with 120 grit. Thinned the second coat to ~10% and rolled on second coat with a glasscoater roller. Tried to tip again, but was having similar results, so I just rolled it. I cut in the fillets with a brush this time (last time I rolled in the fillets using a small foam roller). I thought brushing in the hatch channels and fillets would be a pain, but that worked really well! The roller left some stipple, and the brushed areas smoothed out well and needed very little sanding. I sanded most of it down today with 220 grit. Plan is to finish sanding and roll/tip the topcoat tomorrow. I hope the top coat paint is more self-leveling. I will be using Perfection two-part urethane.