Stringers is the subject !!

[tunnels]

The building of a plug, to build a mold, to build a stringer grid assembly...to "glue" into a new hull...

Building a grid system is definitely a way to go for future use ! Is simple and easy to make and the fitting and attaching speeds up production and holds the hull perfectly in shape no need for extra stringers , also never rots and stays much dryer and is easy to keep the bilge clean and not smelly !!! planning how and what to use the different areas for is important ! ALSO mounting under floor fuel tanks and making space for the plumbing of fillers and vents and wiring looms etc can all be built in
Something most everyone forgets is space under the floor and the fuel tanks are potential buoyancy to displace water in the event of being swamped !!.


After looking at this photo for a few hours I am at a loss to understand the thinking behind what's actually being made !!
, Nice job but I feel is completely gross over kill !!

[tunnels]

Now we are starting to see some action !! Grids made from fiber glass are much better than ply in its edge ! . It grids are well thought out are really useful in many ways ! they don't rot , they support and
make a good base for the floor to be fixed to , they can support and hold under floor fuel tanks, suspended above the hull , thinner ply can be used to make the floors and if done properly under floor storage is easily accessible for odds and ends , and if painted nicely is always clean and dry and non smelly !!

[rock]

What was in there for stringers?

Fir that was so saturated with water that I was able to actually remove some of it with a vacuum cleaner. I do think the composite material would have been better for longevity but the boat is 30 years old and should be good for the next 30. People don't seem to see the importance of sealing a hole in a stringer. As well as the stringers are encapsulated with out breaking the seal they should last a long time.

Rock

[talonkid]

My thought is the same as others on here, the boat should be ridgid. If the boat/hull were to flex, especially when driving at speed, the boat will develop a hook and totally change the handling characteristics. Between myself and my dad we've had a couple boat rebuilds under our belt and I still swear by using the meranti or okoume marine grade plywood. The boats themselves are proof between the before and after of how much better it handles. The meranti has double the plys as normal fir plywood making it much stronger and utilizes water-proof based glues. More so than that it is a 100% smooth working surface so there is no chance of air pockets or bubbles to develop as long as you roll out the fiberglass well.

I'm currently rebuilding a needlenose STV right now and was considering using the coosa for stringers and floor, etc. to go with the "wood free" rebuild but I was quite skeptical after seeing it. I was looking at the 1/2" and 3/4" bluewater 20 and I was shocked and how flimsy it is, would swear that 1/2" sheet rock is more ridgid than it is. Therefore, by the time it has to be fully wrapped in fiberglass to give it the necessary strength (comparable to the meranti plywood) we figured there isn't much weight savings at the end of the day.

We have also found that working with the epoxy is much better than working with a polyester or vinylester resin.

To sum it up, in my opinion the hull should be ridgid, and therefore to get there I would use a marine grade plywood versus coosa. Based on the working materials I would swear by epoxy versus a vinylester or polyester resin.

[tunnels]

what are the steps for fitting , bogging in and securing stringers ?
what glass do you use ??
and why do you use that particular glass ?

[powerabout]

The last Americas Cup mono racing yachts built before the multi hulls, 80' long no stringers, no bulkheads.
Probably more money spent on FEA, design and development than every powerboat ever built added together.

[XstreamVking]

The concave and convex shapes keep the big sail boats from flexing too much. The keel acts as a longitudinal stiffener also. Mast goes from keel to deck so it also reinforces the hull. These boats are not flexing much at the low hull speeds they see. This is where the 0/90/45 glass helps a lot...

[W2F a V-King]

^^^ They are also not skimming the surface at 80-120.

[tunnels]

^^^ They are also not skimming the surface at 80-120.

The stresses and strains on Yacht hulls is totally different to power boats and the flexing is usually taken up using shape to its best advantage and the comprehensive skin laminate frame work of unidirectional fibers running in the direction of strain and stress areas !
Been there and done all those things making racing yachts in New Zealand over many years and South Korea 2007/8/9 for Match racing and there White Tiger challenge.
If you were to make your small power boats using the same kinds of technology as goes into building a Racing yacht they would be probably 1/2 the weight they are !!
Like I said a while back 40% or more of glass used making most powerboats small or big is serving no useful purpose at all !!
You want to see how to save weight then get into small sports planes !! that will knock your socks off for sure !!Gliders are even more technically advanced than ordinary planes and take things to extraordinary limits !
Tunnel boats hardly even touch the water and fly so what's the point of elaborate cores and multi layers of useless glass !
The use of shape to achieve strength seems to elude the power boating industry !!

[powerabout]

The concave and convex shapes keep the big sail boats from flexing too much. The keel acts as a longitudinal stiffener also. Mast goes from keel to deck so it also reinforces the hull. These boats are not flexing much at the low hull speeds they see. This is where the 0/90/45 glass helps a lot...

The keel is a fin has a chord length of about 18" and 12' long with 20 ton bulb on the end, it fits in a tapered box in the hull.
The mast is suspended on a carbon plank that goes from the rigging on one side to the other so the load is not in the structure. A couple of pins hold the rigging in the boat so it all moves together. It just looks like a canoe inside.
Sure they are not doing 100mph but offshore racers are now sustaining 30kts in the ocean so they know something about slamming loads

[tunnels]

WOW SOME ONE HAS BEEN TAKING NOTICE !Yachts can take more punishment and can endure lots more punishment than power boats and as for pounding and abuse because they move and can absorb a lot more than if they were ridged and stiff !!
Even with all kinds of stringers and bits planted inside your little boats at a 100 mph plus there is still movement between those stiffeners that takes place that happens you cant see !! its quite funny when I start to talk about flex everyone gets up in arms and starts waving the fists in the air But I know there has never any mention of Twist which is a different form of flexibility and hulls with not fixed and glassed in floors and are wide open will have twist !!
Cats of any description including tunnels have excessive amount of twist applied to them But its the floors that has to absorb this !!

[powerabout]

I wonder if anyone has done an FEA on a vee bottom to see a thicker composite hull would remove lots of internal structure?
Certainly having a floor fixes the twist issue.
Deck glassed to hull and not bolted is where everyone should be as well as bolting 2 stiff edges together creates a tear along the dotted line failure which you see after stuffing accidents on many boats.

[Krazymaan]

The building of a plug, to build a mold, to build a stringer grid assembly...to "glue" into a new hull...

That should hold at least 150 cuban refugees and six thousand pounds of coke.

[powerabout]

its just the old
we have always done it like that and it works
mentality
as I said the money is spent in aircraft then its straight into waterskis, F1 cars and racing yachts, powerboats take another 25yrs or so
18' skiffs in Australia were built with Carbon nomex or aluminium cores in the late 70's, any stories like that with powerboats?

[XstreamVking]

I have a mid 80's Cajun bass boat with an alum honeycomb transom core. Kevlar laid at keel for impact with stumps and logs....I think it was ahead of the curve..