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post #41 of 355 Old 11-29-2015
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Re: Construction methods (and their trade offs)

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Originally Posted by smurphny View Post
Rub rails of some sort seem like an essential design element of a cruising boat. The protection from a hefty rail to shrouds when alongside pilings, other boats, or many rough, uneven surfaces is considerable. I've often thought of bolting on an additional rub rail.

On the hull/deck discussion, I suspect the quality of the layup, bolt/screw spacing and size, and quality of workmanship is probably more important than the profile.
Most of my clients are using 1 1/4 inch sch 40 stainless pipe for the rail cap ,which serves as a rub rail in such conditions. The only one damaged was damaged in a collision with a freighter in Gibralter in a pea soup fog. The rail damage was the only damage he suffered. He went on to finish his circumnavigation to BC, and the rail still hasn't been repaired.
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post #42 of 355 Old 11-29-2015
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Re: Construction methods (and their trade offs)

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Agreed. Really like grey. Even shows the tannin mustache less than white. Particularly like well done, seamless looking Al hulls. Especially when there's no hungry horse look to them. Keep my boat white and shiny because I want to preserve the gelcoat but that flat grey look seems very businesslike and masculine.

Saw a Gunboat in grey. Very striking and beautiful.
Gray makes a boat extremely hard to see at sea, or even in some anchorages, making you far more likely to get run over.. Any gray is exponentially hotter in the sun than white. Bare aluminium gets hot enough to burn the soles off your feet. I had to paint the bottom of my aluminium dingy white , while in the tropics, to stop that problem.
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post #43 of 355 Old 11-29-2015
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Re: Construction methods (and their trade offs)

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Originally Posted by seaner97 View Post
Ok- I still want to talk about deck to hull joints, but I'll go for the two things that have been thrown out so far.
The perforated toe rail- no doubt it adds longitudinal stiffness to the deck to hull joint as well as an easy way to attach stuff. Aesthetically, I like teak, but it's not as utilitarian. I'm guessing they got rid of these in search of a 'cleaner' look, and as a cost savings measure. Much like pop up cleats, which I think are asking for trouble.

Regarding liners, nothing wrong with them from an engineering standpoint. It's like a hollow core door. Skin carries the loads. The problem is that they are done so that all the systems are either inaccessible (esp plumbing and wiring) or they are broken into prefab compartments, which reduces that efficacy of load sharing and then on top of that they have no accessibility.
Properly done, with multiple access ports, with reinforcing bars around them and proper adhesion to the hull, they would be fine. I've yet to see one done that way. Maybe someone has pics of one done 'right'?
Now that I think about the system that I had called a "Full" liner on my Boat, is not, and not structural at all. There is a bonded grid fully accessible under the sole and bunks then the liner in pieces covers the head, quarter berth and galley just for cosmetics. Although there are small hull areas inaccessible without some damage, nothing is covered that needs normal inspection or maintenance. Now the main and companionway bulkheads are the strength, chain plates bolt directly to the bulkhead. I think I'm "done right" just not the liner you example.
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Re: Construction methods (and their trade offs)

As fibreglass weighs roughly 96 lbs per cubic foot, and sea water weighs 64 lbs per cubic ft, 2/3rds the weight of sea water, it takes one third the weight of the hull in buoyancy, plus sufficient overkill for ballast and machinery, to float it. A couple of inches of foam should be plenty, for most plastic boats. As life aboard almost all stock plastic boats in cold climates is like living in a block of ice , in cold weather, a couple of inches of foam is good insulation , and drastically reduces condensation as well. Wouldn't cost all that much either. Don't know why it is not more common. I guess it shows how most are built for warm, fair weather sailing only, and how the manufacturers squeeze every nickle til the beaver craps.
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Re: Construction methods (and their trade offs)

I have wondered about filling the space between the hull and liner with closed cell ,canned ,polyurethane insulation. You would have to make sure it is closed cell ,as much of it is definitely not.
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Re: Construction methods (and their trade offs)

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Originally Posted by albrazzi View Post
Now that I think about the system that I had called a "Full" liner on my Boat, is not, and not structural at all. There is a bonded grid fully accessible under the sole and bunks then the liner in pieces covers the head, quarter berth and galley just for cosmetics. Although there are small hull areas inaccessible without some damage, nothing is covered that needs normal inspection or maintenance. Now the main and companionway bulkheads are the strength, chain plates bolt directly to the bulkhead. I think I'm "done right" just not the liner you example.
This sounds more like traditional construction and not a liner in the way it's being referred to. A cosmetic liner has been used for 50 years instead of proper ceilings. The newer ones that are 'structural' are significantly different.
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Re: Construction methods (and their trade offs)

Sean is correct Al. Your boat is not what I would call a "liner boat".

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post #48 of 355 Old 11-30-2015
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Re: Construction methods (and their trade offs)

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Originally Posted by seaner97 View Post
Let's try this again. Leaving behind the crud that other threads have devolved into, let's actually talk about construction methods and design limitations. Try to keep it civil and non personal. Try not to brand bash. Try to realize that certain boats have to hit certain price points, but that doesn't mean they can't be seaworthy.
Hi,
New poster with a slightly different perspective which may be of interest to people looking to build or buy a non production boat.

New boats are expensive because boat building is a messy, fiddly, wasteful business with high labour and overheads.

One way to reduce these is "intelligent infusion" which has reduced the time taken to build a one off by more than half, albeit for a relatively specialist boat type.

Infusion is a fairly well known technique which, compared to hand laminating saves time, uses less than 50% of the resin and results in a higher quality job.
The laminate and core are placed in the mould dry. It can be carefully tailored and accurately placed without any of the stress associated with fears of resin curing. A vacuum bag is then placed over the job, the air evacuated and a hose hooked up to a drum of mixed resin. 40 minutes later, the entire job is perfectly wet out. For anyone who has hand laminated it is a huge WOW!
Most infusers use the technique to produce conventional hulls and decks, with all the trimming, shaping and post mould work these require. The future is in using infusion to eliminate this.

Including everything in the infusion that is normally done post mould is minimal effort. Structural grids, landings for bulkheads and shelves, rebates for windows, holes for skin fittings, engine mounts, ring frames, solids for deck fittings, beefing up in high load areas, aligned reinforcement for specific loads, conduit for plumbing and electrics and blanks for fastenings can all be accurately placed then perfectly wet out with no post mould cleaning up required.

The external surfaces are peel plied. Remove it and it is ready for paint. The internal surfaces can be peel ply and paint, left shiny or made flat and skinned with veneer, clear woven carbon, formica or similar materials.

The box moulds are built from sheets of low cost mdf. The shaped areas are wire cut polystyrene foam. The mould is lined with thin plastic sheet so it does not need polishing or waxing. A half mould for a 40' hull takes a couple of people a couple of days to build. Another couple of days and the layup is ready to bag. The moulds are sufficiently cheap and accurate that half hulls/decks can be produced, with male/female joins along the deck and keel, eliminating the hull/deck join and all it's problems.

The flat components (bulkheads, bunks, shelves, benches, etc) are infused on a table. All the edges are finished. Doors and hatches including rebates and solids for catches, glass, louvres, handles and hinges and their surrounds are included so they fit perfectly. There is no grinding or shaping required.

When cured, remove the peel ply and glue everything into one half of the hull and deck. The joins are all male/female so no measuring or alignment is required. Then paint the interior and install as much of the fit out (galley, toilets, wiring etc) as is feasible, which is easy as the half hulls are at floor level and wide open. Glue the other half to it and the hull is ready for external painting. Apart from the paint and the glue, there is no mess, grinding or hand laminating.

The miserable, sticky, dusty boat building work is removed from the process, leaving the builder with the inspirational stuff, which all goes together in less time and cost than any of the conventional methods.

Little of this is new. It is the result of a lot of testing, experimenting and discussion with experienced infusers and builders. There have been a number of hulls built along the way, each one quicker, lighter, cheaper and generating less mess than the one before. The latest are a 60' cruiser being built by Ballotta in Peru for cruising Patagonia and a $50,000 40' racer. I can't post links to these as i am a newbie, but pm me if you are interested.

Limitations? Conventional curvaceous hulls need a little more work than the simple shapes we have used so far.
Drawbacks? Finding leaks in vacuum bags can drive you nuts, but there is an increasingly effective range of tools to simplify the process.
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Re: Construction methods (and their trade offs)

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Originally Posted by rob denney View Post
Hi,
New poster with a slightly different perspective which may be of interest to people looking to build or buy a non production boat.

New boats are expensive because boat building is a messy, fiddly, wasteful business with high labour and overheads.

One way to reduce these is "intelligent infusion" which has reduced the time taken to build a one off by more than half, albeit for a relatively specialist boat type.

Infusion is a fairly well known technique which, compared to hand laminating saves time, uses less than 50% of the resin and results in a higher quality job.
The laminate and core are placed in the mould dry. It can be carefully tailored and accurately placed without any of the stress associated with fears of resin curing. A vacuum bag is then placed over the job, the air evacuated and a hose hooked up to a drum of mixed resin. 40 minutes later, the entire job is perfectly wet out. For anyone who has hand laminated it is a huge WOW!
Most infusers use the technique to produce conventional hulls and decks, with all the trimming, shaping and post mould work these require. The future is in using infusion to eliminate this.

Including everything in the infusion that is normally done post mould is minimal effort. Structural grids, landings for bulkheads and shelves, rebates for windows, holes for skin fittings, engine mounts, ring frames, solids for deck fittings, beefing up in high load areas, aligned reinforcement for specific loads, conduit for plumbing and electrics and blanks for fastenings can all be accurately placed then perfectly wet out with no post mould cleaning up required.

The external surfaces are peel plied. Remove it and it is ready for paint. The internal surfaces can be peel ply and paint, left shiny or made flat and skinned with veneer, clear woven carbon, formica or similar materials.

The box moulds are built from sheets of low cost mdf. The shaped areas are wire cut polystyrene foam. The mould is lined with thin plastic sheet so it does not need polishing or waxing. A half mould for a 40' hull takes a couple of people a couple of days to build. Another couple of days and the layup is ready to bag. The moulds are sufficiently cheap and accurate that half hulls/decks can be produced, with male/female joins along the deck and keel, eliminating the hull/deck join and all it's problems.

The flat components (bulkheads, bunks, shelves, benches, etc) are infused on a table. All the edges are finished. Doors and hatches including rebates and solids for catches, glass, louvres, handles and hinges and their surrounds are included so they fit perfectly. There is no grinding or shaping required.

When cured, remove the peel ply and glue everything into one half of the hull and deck. The joins are all male/female so no measuring or alignment is required. Then paint the interior and install as much of the fit out (galley, toilets, wiring etc) as is feasible, which is easy as the half hulls are at floor level and wide open. Glue the other half to it and the hull is ready for external painting. Apart from the paint and the glue, there is no mess, grinding or hand laminating.

The miserable, sticky, dusty boat building work is removed from the process, leaving the builder with the inspirational stuff, which all goes together in less time and cost than any of the conventional methods.

Little of this is new. It is the result of a lot of testing, experimenting and discussion with experienced infusers and builders. There have been a number of hulls built along the way, each one quicker, lighter, cheaper and generating less mess than the one before. The latest are a 60' cruiser being built by Ballotta in Peru for cruising Patagonia and a $50,000 40' racer. I can't post links to these as i am a newbie, but pm me if you are interested.

Limitations? Conventional curvaceous hulls need a little more work than the simple shapes we have used so far.
Drawbacks? Finding leaks in vacuum bags can drive you nuts, but there is an increasingly effective range of tools to simplify the process.
But introducing a less traditional, but also potentially more problematic joint (if this joint pulls apart you're straddling the ocean), and reducing the mechanical advantage of the traditional deck as the joint is down the middle and the spreading of the forces can't be done by the deck skin. Not saying this can't be done or done well- but it's still a tradeoff. And that's the point of the thread- it's all tradeoffs. You no longer have to worry about a deck to hull leak, now you have to worry about one right overhead that will want to pull apart by the very nature of the structure of the rig and one that runs right down the center of the hull. Call me old fashioned, but I'd prefer a completely vacuum bagged hull deck then joined in the old fashioned way as when it fails it's a little less likely to fail in a fashion that that Oyster did. Very cool concept and production, and I would expect that they would be just fine for a very long time, and if you reinforced the keel and deck seams with many layers of glass properly done both internally and externally, it might be almost as strong as a traditional method without the deck to hull joint leaks.

Ocean- that which covers 3/4 of a world made for man, who has no gills.
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post #50 of 355 Old 11-30-2015
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Re: Construction methods (and their trade offs)

Vacuumed infusion is great, but there are real issues that have to be taken into account. The major issue is that if something goes wrong while doing a vaccume infusion the entire part may be junk. Imagine laying out all the fiberglass, tons of epoxy, thousands of pounds of core, and the infusion line gets a kink half way through the process... Not the shop has to eat the entire cost of the materials and labor since it is unrecoverable. Shop practice MUST be flawless, and the flow process properly engineered or major issues can occur.

Secondly infusion may require changing laminate schedules or core thickness. Particularly with thick lay ups the reduction in thickness from infusion can result in a substantial decrease in the parts stiffness. This needs to be accounted for.

All in all infusion is great for large complicated parts, but it isn't a panacea. It requires improving the quality of every step along the way to maximize the return.

Greg
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