C17 in New Zealand.

[OneWayTraffic]

Bit of progress this weekend. Made some fibreglass tube by rolling biaxial tape around a taped pool noodle. Broke it free the next day and set into my transom scupper holes with the use of a lot of putty to fill the gap entirely. Then a few more layers around the tubes overlapping onto the transom. Will have a bit of work to do to fair it in properly, but with all the things I'll have on the transom minor fairing issues won't show.

Speaking of things on the transom I glued some 18mm ply samples to a piece of pine, then glassed it in on a fillet. This is the underneath side of what will be a small boarding/swimming platform on the transom. The transducer will go underneath out of the way, and the platform will both protect from damage, and deflect spray.

Also a photo of the sheer and chine UHMWPE strips. Quite happy with how they've turned out, but painting around them will be a pain. I did think about installing after paint, but I will always value strength over looks. I wasn't keen to glue them onto paint.

[OneWayTraffic]

Ok I don't know if the fairing is finished, but I do know that I'm finished with it. I've got the best finish I can manage given the circumstances and put two coats of epoxy on the hull today. Roller coats with 140ml of epoxy, two spoons of Aluminium powder and one spoon of Cabosil in each batch. Some slight stipple from the roller, which I kind of like.

I've got some tiny little irregular spots visible only when I look down the hull sides. I can't feel them with a finger, or see them side on. I've not put any high build primer on yet, that will wait until after the flip when I'm ready to paint. With small bits of grass and insects getting in the epoxy I'll try to do that inside.

I also had a fair few drips on the UHMWPE rubrails. I used a heatgun and a scraper to get rid of most of it, and then scrubbed with a Scotchbrite. Turned out ok.

If the finish turns out to be substandard I'll put a vinyl wrap on the upper side. About $700 a side if a pro job.

Flip will be next week weather permitting.

[OneWayTraffic]

Photos

[TomW1]

Looking good guy!

Tom

[OneWayTraffic]

Well the boat building has gone on but I've been remiss in not posting updates.

Quick recap. Like Sideslippa and his OB17, and some of the earlier PH16s and PH18s I decided a few months ago not to remove all the inner framing. I posted my reasoning back here so won't go into it again.
viewtopic.php?p=468821#p468821

Flip was a piece of cake, four guys walked it out of the tent laid it down, rolled it over, and carried it back in. It's sitting on blocks under the keel with 2x6 supporting under the stringers. I'll rig up benches or something to support the front when I get there. At the moment though it's solid at the back.

Then started glassing the back boxes, one at a time. I'm not a fast worker so prepping filleting and glassing one a day is about all I can do. Two layers overlapping up onto the stringers and frames. Tape as well to bring up to spec where needed. Few bubbles here and there, but no disasters. I thought about using a single layer on the inside, but I'm out of tape so it's easier not to cut and lay tape from my roll of wide biaxal.

Looking back towards motorwell. I am still thinking about what this will look like, but am likely to go with the 4" setback bracket that came with the outboard, so have cut it a bit shorter. E-tec 60hp only needs 360mm of space, and I will have more in case I need to fit another OB later.

Cut out Frame D. I've cut it down so I can run the inside stringer cleats the full length unbroken. 18mm by pine clears will add significant longitudinal strength, and I already have the wood. Left some in place to locate the side benches. Current idea is to have these running back to the motorwell, and portable tanks, battery and storage under.

[Fuzz]

You have made good progress It sure is nice to get back to building after all that fairing

[OneWayTraffic]

Yes. The fairing is not done, but I am done with it. I might name my boat "sanding fatigue" or "tired of grinding."

Amazing difference once the glass goes on. Forward where it's not sanded there's detectable give where I stand on it. Walking on the glassed area feels like walking on concrete.

[OneWayTraffic]

I've started giving some thought to foam vs airtight compartments vs compartments with breather holes and inspection hatches. The designer recommends two part foam, and many on the Bateau forums have used it successfully, but there's also some horror stories out there, often (not always) involving water getting in through unsealed holes and penetrations.

My thoughts:

I don't want fully foamed compartments below the waterline. I'd always be worried about water getting in there even if it is unlikely. Neither do I want nothing but airspaces. I'd be concerned about water getting in there and pressure from the air expanding and compressing with temperature changes working at weakpoints in the structure. Also unlikely but...
On the other hand hatches and limber holes can let water in as easily as out. In the worse case of a swamping or some kind of structural damage to the hull the boat could go under very fast without some flotation.

So far this is what I'm settling on. I'll have several compartments in the hull under the floor. I'll use some of my already bought and glued together EVA foam pads (about 150L) to fill some of this, and some medium density pour foam (65kg/cubic metre) to fill strips near the stringers of the central underfloor compartment, supporting the sole and leaving the central area free for ventilation. Bung at the back of the central compartment, small plugs for the side compartments, with 2mm breather holes up at the bow end to equalise pressure. I'll use a hole saw to allow air to flow through the frames where needed.

Above floor flotation will be down the side walls above the floor level so I can get my toes under, and also in semi watertight storage seats etc. Looking at about 300L of foam buoyancy which should be enough since the hull material floats, even with fibreglass skins. I just need to float the motor, battery and crew.

Would be interested in thoughts or comments, though there has been a lot written on here about foam.

[Browndog]

The horror stories that you often hear about foam in compartments under the sole is most often related to older production boats.

Several things to consider. Most production boats do not use epoxy resin. They use polyester resin. Polyester resin is quite porous even with newer polyvinyl ester gel coat. So water tends to infiltrate the fiberglass hull more in a polyester built boat leading to osmosis induced hull blistering, core delamination and saturation of the cores. Older types of foams that were used were also not as resistant to chemical breakdown and water saturation. The fear of wooden cores is generally a result of using polyester resins instead of epoxy.

Epoxy is a very good sealant and its waterproofness is substantially better than polyester.

The specification of quality marine plywood in most stitch and glue designs further improve the water resistance of the epoxy, fiberglass cloth and plywood laminate.

Using wood that has not been coated with epoxy and inferior grades of plywood in moist environments is not recommended regardless of whether foam is used or not.. That is why hull penetrations after manufacture are a leading cause of water intrusion. For example, drilling a hole or screwing something to the hull and not sealing the core provides an unsealed edge where water tends to wick from the unsealed edge into the core.

The reality is that air intrusion is much harder to prevent than water intrusion.

Air contains water vapor which will ultimately condense due to ambient temperature, pressure and humidity changes.

Modern two part polyurethane foam is very resistant to chemical breakdown and water saturation. A testament to its durability is that it is frequently being used now in place of concrete for underground fence post support for continuous unprotected outdoor use.

But there are alternatives to foam. Air filled containers or bags are frequently used in kayaks and other light craft to fill under deck areas to aid buoyancy.

If your boat will mostly reside on a trailer on land when not in use, the storage conditions are more likely to impact the longevity of the boat than anything. If the boat will spend its life in the water in a slip, than bottom paint will be necessary.

A well cared for boat built with high quality materials should outlast its creator.

[Cowbro]

I don't have tons to add, but I saw at one point someone that used plastic balls, like you'd see at a kids indoor play area. (Roughly 2.5"-3") in diameter. You could install hatches and fill under the sole through the hatches. You wouldn't get 100% floatation in the space, but it would still be pretty high (75-80%?). Then if you ever wanted to remove all of them you could fish them out through the hatches and fully inspect/dry the hull as needed.

I like to be able to inspect every part of the boat after every outing. Part of my cleaning routine is to open up every hatch and check for water or moisture and then let all of them air out for an afternoon in the sun.

Similarly, common practice on sit-on top fishing kayaks is to fill the hull with pool noodles so if you ever get a leak the kayak will stay afloat. I've never had to test it, but it is a very nice piece of mind and easy to remove for service.