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Bill H

Boat Building Techniques for the Philippines

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Bill H

LOL, I don't think you guys appreciate how bad the local plywood is.  A decent marine ply 1/4" thick (6mm) should have at least 5 ply, the local has 3, huge difference between a 3 ply and 5 ply sheet.  It falls apart in the water if you get any failure in the paint.  I've had samples complete delaminate in less than an hour.

 

With all due respect, I'd stick with epoxy and glass over ply here.

 

PIM - I contacted Hartley's looking for some stock Ferro plans and could not muster a response of any kind.  Have they gone out of business?  Second question:  What about the bird mesh?  Is that available in the Phils, I've never seen it.

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Haki

LOL, I don't think you guys appreciate how bad the local plywood is.  A decent marine ply 1/4" thick (6mm) should have at least 5 ply...

 

we are selling this stuff, the best marine plywood we get is Santa Clara. The  1/4" comes with 3 plys not necessarily hardwood and only 5 mm thick.

 

Regarding china plys, one normally would see - cheap - scrap which looks like being rescued from an end as firewood

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angbumabasa

The best one can do with the present 'marine' plywood is inspect and discard any knotted patching during the manufacture. I've seen the locals doing their best on inspecting and accepting only 'clean' pieces. On 3 ply, the hidden layer can have all kind of knotted repairs. Framing here is largely performed with un-aged, un-dried hardwood. The problem there is the dimensional change taking place there, which is easily seen in our split bamboo, hard wood framed, gate. We have about twenty powered bancas dry docked here at any one time. Some new, many refurbished. Some even with softwood framing. I see the failures almost daily. Outriggers: cross arms question mark shaped, bamboo, thin enough to be resilient are preferred. Outriggers themselves larger in diameter tha a SMG bottle, strait as possible with a wood nose piece rounded or conical. Mounting in plan is closer to the bow, and in elevation bow up. In rough weather, departing or arriving, I see how well that works, making most accidents, such as being breached by waves, operator error.   

 

Oh, as an after thought, plenty of paint.

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PIM
....

 

PIM - I contacted Hartley's looking for some stock Ferro plans and could not muster a response of any kind.  Have they gone out of business?  Second question:  What about the bird mesh?  Is that available in the Phils, I've never seen it.

Hartley's are a reseller of boat designs produced by others. They can be found here. I don't know to much about the designs they sell - below my league. I only work with commercial shipping.

 

Bird mesh? The mesh that should be used in ferro-cement vessel construction is of the welded type 12.5mm x 12.5mm x 1.3mm to 25mm x 25mm x 1.6mm, not exactly what I would call "bird mesh". I believe that mesh of these sizes is available in the Philippines. Where, I know not.

 

In a commercial environment, you are looking at a minimum hull thickness of 18mm up to about 37mm for a 30m vessel. With less stiffening, the hull thickness is even greater. One design I did for a defence forces client had a hull thickness of 100mm at 60m length.

Edited by PIM

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Oz Jon

is that similar to "chine ply"?

 

 

No.

 

Chine construction uses "full thickness" flat sheets, slightly curved and a bit twisted longitudinally. It needs good quality marine ply.

Usually only 2 (maybe 3) long sheets each hull side, so just a couple of (basically flat) changes in direction transversely..

 

The construction I described (photo below) can do double curvature - longitudinally and transversely.

You effectively, make your own double-curved ply sheets, out of thin narrow ply strips, on-the-job.

It is also known as "cold- molding".

 

It takes much more labour to do it, but you can use lower grade ply, with good epoxy.

(unlike polyester resin, which is not waterproof, epoxy resin is truly waterproof)

That's why I think it could be a good boat building method for the Phils.

 

Fortunately labour is cheap in the Phils (and it gives a few families an income).

 

You can make good-looking, very efficient, low drag hulls this way

post-15613-0-88231500-1439708997_thumb.jpg

Edited by Oz Jon

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PIM

What Oz Jon is showing is termed a cold-moulded hull. He is correct in that it is a good construction medium to use, particularly when plywood is of questionable quality and/or the hull form has not been conically developed.

 

Conical hull development is an art in itself. Some computer programs have tried to do this, but none have been yet able to perfect the technique. I still do it manually, by hand. It takes a good eye and experience to do it well.

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Oz Jon

Another advantage of "cold molding" is that, unlike other ply-sheet techniques (which require shaping), there is no waste plywood.

 

You cut all the ply into narrow strips and any excess length of any strip, when layed-up, can be cut off and butted onto a later shorter strip.

 

Zero waste!

 

And working with timber (even ply) feels good!

 

Who says Engineers have no souls! - Lol!

Edited by Oz Jon

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darrener

I wonder if any of you knowledgable guys could give me your opinion on the stitch and glue method of boat building, and is it feasible in the Philippines ????

it seems to be a fairly easy construction method that appeals to me......

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Oz Jon

I wonder if any of you knowledgable guys could give me your opinion on the stitch and glue method of boat building, and is it feasible in the Philippines ????

it seems to be a fairly easy construction method that appeals to me......

It's a fine lightweight technique for small catamaran hulls (particularly racing hulls, up to about 25ft OA) but I've not heard of it being used for bigger boats (ocean going 30-60ft maybe). Some Olympic classes used it.

 

It is usually used as a compromise technique, to squeeze the maximum possible amount of "double curvature" and stiffness out of a flat ply sheet.

 

It requires first-class material, when pushed to its limits.

 

If you cannot get good reliable marine ply, then I think cold molded local ply or ferro-cement are probably the 2 best candidate techniques for economical bigger sea-going boats given the material and skills available in the Phils.

If you've got the money, then epoxy-foam sandwich is the way to go.

 

However, for any technique, a design by an established boat designer is essential.

DIY sea-going boat design is a bad idea - boat design is more complicated than it looks! - not a game for amateurs!

 

Don't be deluded and underestimate requirements for island hopping in the Phils, just because the distances are relatively short.

I've encountered 50knot wind gusts and 3 metre waves while island hopping in the Phills. Not to be taken lightly!

 

Plan for survival if your sails are torn to shreds and/or your engine fails! - It happens more often than you may think!

Edited by Oz Jon

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darrener

It's a fine lightweight technique for small catamaran hulls (particularly racing hulls, up to about 25ft OA) but I've not heard of it being used for bigger boats (ocean going 30-60ft maybe). Some Olympic classes used it.

 

It is usually used as a compromise technique, to squeeze the maximum possible amount of "double curvature" and stiffness out of a flat ply sheet.

 

It requires first-class material, when pushed to its limits.

 

If you cannot get good reliable marine ply, then I think cold molded local ply or ferro-cement are probably the 2 best candidate techniques for bigger sea-going boats given the material and skills available in the Phils.

 

However, for any technique, a design by an established boat designer is essential.

DIY sea-going boat design is a bad idea - boat design is more complicated than it looks! - not a game for amateurs!

 

Don't be deluded and underestimate requirements for island hopping in the Phils, just because the distances are relatively short.

I've encountered 50knot wind gusts and 3 metre waves while island hopping in the Phills. Not to be taken lightly!

 

I was thinking about a mono-hull sport fishing boat of around 20 ft.... there are several designers selling plans on line...... but if the plywood is no good here then maybe not such a good idea...??

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Oz Jon

I was thinking about a mono-hull sport fishing boat of around 20 ft.... there are several designers selling plans on line...... but if the plywood is no good here then maybe not such a good idea...??

 

{I edited my post slightly before you replied} - sorry about that!

 

That's outside my experience of yachts and sail/power catamarans.

 

I suspect that many people have cold-molded power boats that size.

 

However, that's not a very big boat, so maybe you could afford to build it in epoxy-foam sandwich?

That is the best available current technique (without getting involved in exotics, carbon fibre, etc).

 

But you need to find an established/reputable epoxy-foam / cold-molded ply designer.

 

If you plan going to sea, please choose a closed deck design!

Edited by Oz Jon

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PIM

I was thinking about a mono-hull sport fishing boat of around 20 ft.... there are several designers selling plans on line...... but if the plywood is no good here then maybe not such a good idea...??

Darrener, for a small (6.0m) sport fishing boat, I would recommend twin-screw, hard-chine, mono-hull of either solid FRP (fibreglass) or, if lighter weight / higher speed is required, foam sandwich. Neither of these materials are cheap to purchase and, to be properly built, needs a suitable building environment and good quality control.

 

A hard-chine cold-moulded plywood sport fishing boat could also be considered.

 

At 6.0m length, I would be restricting this vessel's usage to relatively protected waters and in the Philippines to within about 30 minutes travel time to a port or safe haven.

 

One of my current projects is a 25.0m foam sandwich commercial sailing catamaran being built in China for operations in New Zealand. This is the first time that the builder has built in foam sandwich, so I need to guide them and watch them like a hawk.

Edited by PIM
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