Building a stitch & glue boat in Fiji

[Saqa]

Hi fellas
I am currently located in Fiji Islands. I am trying to make a s & g boat about 4m long. As its a first build I am trying to learn on the go. I am not familiar with a lot of boating jargon and building product brand names

Its a difficult task doing it here. I have been reading thread after thread on various forums and most of the products are unavailable here so I have to substitute and find alternatives. I am unable to order online as shipping costs to Fiji are huge!

There are a lot of little things about the building process that I dont understand as well. I joined this forum hoping for help understanding these. I am not looking to be spoon fed though and I mention it because I too would like to understand epoxy fillers and constituents

When I lived in Australia I had a rod building biz so am familiar with rod building epoxy and glue. I also have a table saw that I made with a circular saw, jig saw, drill, electric planer, jack plane and a heat gun

I am keen on DIY and custom work and felt like making working on the design instead of using a ready to go plan. To that end I downloaded a program called Hulls. I have the space to make a 4m boat and that is the size I am going with. Marine ply is not available here currently so I picked up 6 sheets of 9mm exterior which is made from the same woods and glues as the locally made marine grade. The only difference is the voids. This ply does have some but very little showing after cutting and nothing has broken from the bending into shape thing. I think I am good here

The design
The waters I am fishing can be classed as lagoon, but its a huge lagoon with the barrier reef way out wide and the inside dotted with islands. The worst of conditions are chop about 2 feet and huge winds when the trade winds are really pushing. Most of the boating will be done on the lee side of the peninsula. The Hulls progie came loaded with lots of designs. I picked one which resembled a lot of aluminum boats used in Oz that I have fished out of and found acceptable ride in the conditions I will be fishing here. The bow that a decent bladey vee and quickly changes to a shallow vee after the first third of the length. The width is 1.1m at the sole line and 1.4m at the gunwales. I am planning to install a short deck/seating at the transom and a short deck at the bow again seating height about 40cm off the sole. The sides are 50cm high









I am calling her the "Saqa Seeker". Saqa is the Fijian name for GT. I plan on throwing poppers for GT around the bommies and jigging around the dropoffs and livebaiting. Hoping she is stable enough to stand and cast, if not I am thinking of adding outriggers like the ones used on kayaks, short pontoons on longish arms fixed near the rear deck area that can lift and rotate forward to rest on the front deck when underway. The engine will be a 2 stroke 8hp yamaha enduro borrowed from the inlaws and I will later get a 10 or 15hp when funds permit. I also want rowing ability for exercise

So thats the design, I have cut the poly and already stitched it once to see if it all fit together, it does I have changed the transom area. I cut the side panels at a reverse angle but fitting the transom vertical to form boarding steps and **** factor looks. I did that as I thought it might not be a good idea to climb into the boat from the sides when boarding being the boat is narrow. I cut out a section in the middle of the bottom panels at the transom to get the leg down between the steps


I have taken the panels apart again to glue the the butting plates which I forgot the first time around ready to stitch it again and moving forward is where I run into some probs and need to learn more

Firstly
When I stitch, how do I lay the panel edges? I have followed a lot of threads on various forums and done a lot of googling but unclear. The usual advice seems to be to retain some gap for chunky gluing with the thickened stuff but another well informed contact has advised to chamfer the edges for thin glue lines. Not sure which way to go. I have found some marine epoxy glue here. Its really thick stuff that can just barely be poured. I dont know if I need to use this neat or mix something to thicken it further. It will drip through a wide gap of a few mils. I can put duct tape behind the seam though

So fellas, any advice on seams? Your assistance and education will be much appreciated, thanks and regards
Jon

 

[michael pierzga]

Panel edges dont touch. You want the panel to float free and be fair.
Rounding the edges is good practice...sharp edges and tight ply to ply joints can create a resin starved joint. Sharp edges can also bind and keep the panel from floating, laying fair. Many times builder insert spacers into the panel joints to keep the ply panels from contacting each other. Small nails perhaps 2 mm in diameter are typical as the spacer. Wood, plastic. Anything will work. Use as few cable ties as possible when joining panel....less is best.

Glue lines are not a concern with epoxy stitch and glue. Naturally if you make huge glue lines, fillets, you waste precious epoxy
The key to good stitch and glue is correct epoxy fillets , biax 45 45 fabric tape and working wet on wet to create strong chines.

a good reference manual for your workshop.....http://www.westsystem.com/ss/assets/HowTo-Publications/GougeonBook 061205.pdf

This epoxy is non toxic and evidently easier and cheaper to ship

Might be worth a look. http://www.entropyresins.com/home

 

[upchurchmr]

Radiusing the edge of the panels makes it easier to align them.

The kit kayak I built specified pulling the edges together - in contact - this gives you a chance of them staying aligned when you might have to twist the hull panels to get the boat straight, before gluing the joints.

First put un-thickened epoxy on the seams to allow it to soak into the wood (5 minutes) then put thickened on the seam. I let this cure before making the fillet. This again helps insure the boat panels are not twisted from the force used to make nice fillets (not much force, but it doesn't take much to twist things)

If you are going to use this boat with a motor at higher speed the glass fabric greatly improves the strength. You don't need to buy 45 degree cloth, just cut regular cloth at a 45 degree angle, same thing.

Adhesives always provide the highest strength with minimal glue line thickness. Some people think that because epoxy will fill a gap that causing a gap is better. It is not for strength.
Additionally with glass taping the seams inside and out, the actual benefit of the epoxy bridging the ply edges is minimal. The glass gives all the strength. The real benefit of first gluing the edges is to fix the boat shape for later work. You actually can move a kayak without fillets and glass without worry.

There are lots of successful ways to do this, differences of opinion just show that.

 

[Saqa]

Thanks for the input guys

Micheal I have just downloaded that west systems pdf, looks like a good read over a cup of coffee

I havent had any luck finding fillers for regular epoxy so ended up buying the epoxy glue thinking I might be able to just use that. Rest the seams on the inside edges and fill the vee formed outside with the glue? Will that be a way to go? I have tried to stitch it so that the inside edges meet and using binding wire loop twisted with a nail end lets me do that without the panels trying to climb over each other. Could it be a workable compromise between the two systems?

Lol fg cloth and tape is another battle here. The only thing I have been able to find is something called 600gsm roving in fg. This stuff is like thatch matt i.e equal thickness strands in both directions woven, there are no threads or stitching in it that I can see. The weave on the cut edges fall apart easily with lack of care. Its hard to cut with regular scissors but I do have a good set of tin snips which might do the job. I cant find any tape other then drywall tape which is fg but only about 2" wide. If this tape is not suitable, can I use the roving to sheath the panels after the gluing and filling? I am wondering if the overlapping edges will give the same effect as taped outer seams?

The other product I have been able to find is something called dynel. Its twice the price of the roving. I previously made a polystyrene foam core canoe and used dynel as sheathing over nylon-polyester fabric over the hand shaped foam block. The result was very good and durable. A local resort uses this to hurricane proof their out door deck and canopy and it seems like would be ok for the inside seams. It is easy to wet out and contour over the inner curves and folds without needing thick fillets. In the pics below you can see the ply top and bottom plates for the canoe. I used the dynel sheet so that its edges overlapped each ply plate and fix together encapsulating the foam. Over that was a huge sheet of the nylon-polyester fabric which is very stretchy and about 2mm thick unstretched. I pulled it up and pinned it to the top ply plate. Intention was for it to be a holder/filler for the epoxy. The epoxy saturates it and cures in place forming a synthetic fibre and resin skin. This fabric is damn strong too and I been tempted to use it to sheath the new build instead of the roving. It dents if punched hard when cured if there is nothing behind it but a hammer doesnt break through to the foam





Well getting back to the point, are the overlaps in the sheath of 600gsm roving a workable alternative to taped seams and is dynel ok for the inside seams? Thanks again, the help is much appreciated

 

[El_Guero]

Saqa,

Mix sawdust with epoxy for your filler.

wayne

 

[michael pierzga]

Stitch and glue ply boats are easy to build but the problem is that they need specific materials. Medium weight fiberglass cloth ,epoxy resin and fillers

600 Roving is very heavy and hard to use. You certainly could use it but It will be difficult to make it bend around corners and use alot of resin.

Better to search again for standard fiberglass cloth. 300gsm would be good all purpose cloth.

Dynel is not structural cloth, its used because it resists abrasion. Very good for surfaces that you walk on.

In areas were sticth and glue materials are imposible to buy, its better to build a plywood on frame skiff.
for you next boat , you should have a look at these skiff plans provided by the FAO, united nations.

These are excellent boats built with exterior quality plywood on avaible local timber frames . they require no or little exotic material. http://www.fao.org/docrep/007/y5649e/y5649e00.htm

 

[Saqa]

What is the 600gsm roving fg material known as in other countries, USA, UK and Oz?

Lol I have so many questions in areas I need to understand further, dont know whether to post them in this thread so anyone answering can see the build its applicable to or whether to create individual threads for each question. Thanks to you guys above for responding

 

[PAR]

600 GSM roving in the USA would be called 18 ounce roving. This is a heavy reinforcement, not typically used on seams, except in large builds (30' boats).

You want to use cloth of a knitted biax, preferably a biax, as it's stronger for the same weight.

If your panels are well shaped, they can touch and having them touch can be helpful in alignment. It's wise to back cut the panel edges so you can force thickened epoxy into the seams, which helps seal the end grain, the most vulnerable part of the panel.

 

[Saqa]

Thanks PAR, I had already bought the roving since it was the only cloth to be found here. I am considering using it as a very wide tape and hoping it works that way. Using a wide section to cover half the wide of two adjacent panels instead of using a wide section to cover each panel and overlapping the seams. Hope that makes sense. The roving was expensive and I hope it works and any additional strength I obtain from using that weight will be a bonus around coral

Digging through the forum I came across this post in another thread and have quoted it below. A really clearly written explanation that I found easy to understand and follow

As Gonzo said, its totally up to the builder, and the angle of the two sheets will have a lot to do with how they 'sit'

Where the 'planks' are at small angles, you will get nearly a butt join, but as the angles increase in the middle, you will usually tend to push them to the position where that the two inner edges are touching, and exposing the raw edges of the plywood for filling. If you don't align the edges on some plans, and let one or other of the planks overlap, you may get build errors as subsequent planks are two low or high, especially on multi-chine boats.

Sam Devlin likes to put a bit of a chamfer on the inner edge of his planks, which makes them easier to position. This works well, but means extra trouble for the builder.

On a 'flatbottom', if you had to have one or the other overlap, I would be inclined to have the bottom panels under the sides, to provide a bit more support for the sides.

All in all, I don't think it matters that much, except for ease of building.

Thank you rwatson

I have restitched just like that and all of the seams have the inner edge touching except for the flare area at the bow. Here the inside and outside edges are level and a few mm of gap. I think this could be it. One area of concern now is the transom. The transom in my design is vertical while the sides have a reverse slope. This means that the transoms lower edges do not sit level with the sides and bottom but recessed into the hull. Stitching this makes for an overlap joint and I am going to restitch that and use matchsticks to create a gap to insert the glue. I can also apply the glue to the area and then stitch without the matchsticks and the stitches becomes the clamp. Unsure as to how to proceed with this.

In the meantime I am going to put the thick marine epoxy glue into an area of the longitudinal seam and see how it goes on and if it needs additional thickening. Wish me luck

 

[rwatson]

Be aware, all of this alignment problem is purely academic if you dont have enough reinforcing around the panel edges..

None of the panel 'touching' techniques here are worth a pinch of salt, unless you have sufficient re-inforcing in the form of fibreglass on each side of the join, or substantial 'chine logs' ( wooden stringers ).

If you are stuck with only rovings as reinforcing, you will need to incorporate some wooden structure in the inside of the join. Rovings have insufficient structural strength, and frankly, are not worth using.

You will get better strength by epoxying in triangular or square section timber reinforcing on the inside of the joins.

I can see all the panels bursting apart in the middle of a substantial chop if you dont get the reinforcing correct.

 

[Saqa]

Thank you Mr Watson. I have just applied epoxy glue along the outside seams and going to follow that up with fillets. Then I guess I am going to put the boat on hold until I can locate some fg tape. I have a feeling that the supplier has incorrectly listed the fg I have as roving. Will google it until I can confirm what it is and will post pics here so someone can hopefully help identify it. It looks like fg weave with the glass running in two directions and very strong. Looks like the stuff on the butts of some wilson fishing rods

 

[rwatson]

Good move. I sympathise with the difficulty in getting the right stuff in remote locations.

 

[Saqa]

http://www.jamestowndistributors.co...=4099&familyName=Fiberglass+Woven+Roving+18oz.

This is the stuff that I have 10m of in 1.2m wide

 

[michael pierzga]

600gsm roving

 

[Saqa]

Thats the one Micheal. Is that ok to use as tape?