Monday, April 26, 2010

Stringers,more stringers,mooooore stringers !

İ am obsessed with this building. İ see stringers everywhere İ look at ...... ! All İ think is boat building !

Side panels stringers, the nano filet and the 5 minutes epoxi miracle

After the hull stringers were all placed and reinforced with aramid fiber, time came to strenghen the hull sides.
İ did exactly what Ben did and that is one of the advantages of being a little bit behind.....! Thanks dude. So İ went with simple 2 inches strips of ply, which as a matter of fact ended up being much more than that in the middle due to the curvature.
To place those stringers at their correct location İ first marked the middle of each panel (from sheer to shine) and trace a line. İ tried to have that line as smooth and balanced as possible over the entire hull from f214 to f 53.5.

To shape those stringers to their correct size İ basically used a very high tech piece of eyes ! No rocket science there.
To make it easier on myself , İ used a straight wooden stick cut to the exact length for each panel stringer then placed it on top of the panel center line İ drawn, from frame to frame. Then İ looked carefully at the gap that showed underneath that stick. (sorry no picture) Measured gap at 1/4 length, middle, and 3/4 , took the stick and those gap measurements back to a leftover plywood piece, marked those measurements and cut. All it took afterwards was a little hand file and fine adjustments to make it almost perfect in all cases.
Then came the Nano filet and the 5 minutes epoxi miracle.

İ have to admit that although İ bought that 5 mns epoxi, İ was not really found of it before and did not use it for bottom hull stringers. There was actually no need to support those bottom hull stringers before actually fileting and taping. But for the side panel stringers it was a totally different story ! So the 5 mn epoxi came to the rescue and the Nano filet came around. Basically İ just did really small filet with silica /5mn epoxi putty.

The purpose was just to hold the stringers in place before actual fılets were done and that really worked 100%.

As a matter of fact here goes a little explanation on how İ held those stringers in place in order to "nano filet" them. İ used the largest clamps İ had and left it hang inside the hull. Then İ used little left over 2x2 blocks (those are my work bench leftovers) and placed them right underneath the stringer to make sure it was perpendicular to the side panel.
İ carefully closed that clamp until everything was aligned with the previously drawn panel middle line and used masking tape to hold the clamp from sliding back.
This was necessary since the clamp was not actually clamping or grasping anything but rather was just supporting the square block on top of which the stringer was laying.
Maybe 5 mns to get the set up perfectly aligned for each stringer, many runs to the other side of the boat just to make sure that all stringers (from bow to stern) looked aligned and seemed to flow as one single giant reinforcement, and then the Nano filet were applied.
5mns after, everything was removed, all stringers were holding tightly and normal filet / tape was applied.
Working on those stringers is not a dificult operation but overall İ would say it is very time consuming. İ spent a good amount of hours to finish the job. Another thing İ am using copiously spending with all those frames and stringers is resin and silica. İ bought 1kg of silica which came in a very large bucket and İ thought it would last me for ever, but to my own surprise it is almost finish. İ will have to buy another bucket !
Next steps for me are:
-finish all stringers (between f18 and f53.5) and maybe some more to support cockpit sole and decks
-finish keel and keel box

Reinforcing the reinforcements....

Since İ had already played with Kevlar for strengthening some frames and had quite some material at hand, İ decided to use it again to reinforce the hull stringers.
Again, İ really found this material to be difficult to work with. Maybe it is just the stuff İ bought but it is hard to cut decent tapes or strips out of it, and it is even harder to do a nice lamination.
As before, the strips were cut with a heavy duty pair of metal scissors. İ also cut strips of paint drop plastic sheets on top of which İ saturated the aramid strips.

The whole thing was then carefully placed on the stringers which needed reinforcement. İ intended to leave the plastic sheets until the whole thing cured but, this time İ took it out as soon as the kevlar was set. This allow me to work the edges a little bit more and get a better results.
Even if it is not the cleanest lamination job around, İt sure is very,very strong.

Cockpit stringers

İ finished epoxing the hull stringers. No real issue there except for the fact that one really needs to be creative in order to find a way to laminate them without setting foot inside the boat.
İndeed, my 83 kgs would bend the hull plywood downwards making it impossible to laminate from the hull, which would have been really convenient.
So it might seem like a simple issue to solve but be my guest ! İ ended up doing some contorsionism laying belly down on my magical alu stair wich İ had placed flat across the hull....
Not a pleasant scene, İ reckon. At 42 years of age and 3 broken back vertebra, İ am not really as elegant as those Cirque du Soleil tiny Chinese acrobats....
Anyways it worked out pretty well and my bottom hull is now really strong. Those stringers make all the difference.

On the picture below, you can see the front stringers which are actually the fwd berth supports, placed and aligned but not yet laminated. İ used a string which İ pulled all the way from the transom to make sure all stringers were perfectly aligned. Hard to take a picture but all hull stringers from f214 to f53.5v are now pretty much forming a straight line from stern to stem.
Should be pretty efficient at adding rigidity to the whole hull and distributing efficiently load forces on the keel box.

Thursday, April 15, 2010

Porcupine look is gone for good

Everybody keeps on saying the same thing but : it is amazing what a coat of resin on your boat interior will do to its appearance...! Wonders !

Looks pretty cool.....I am happy with it. No more ties on my hull and all frames nicely laminated. The boat is 'happening'. Too cool to see what you can do with your own hands and a little bit of free time !

Next will be hull bottom and side stringers.

keel box area reinforcement

Time to place some reinforcements around the keel box area. The sides of the keel box ,by the way, are cutted , laminated and ready to be placed in the boat. The only problem is that I have not finished the Monster Oak keel and have been dreaming about going with an aluminium extruded profile made by Krona Boats (more on that on the forum). So the keel box itself is postponned for now.

I have measured a zillion time to make sure I had all the space needed between f.124 and f.110, and then went for it and reinforced the whole thing:

-on the fwd face of 110, I placed a long piece of ply at the bottom of the frame going from hull side to hull side. It actually looks just like the original f110, but it is actually a reinforcement glued on the back of f110 extended cockpit version

-on the rear face of 110, that is in between 110 and124 right where the keel box will be, I added another reinforcement. It is a simple rectangle that fits right in the middle of the bunker cuttouts all the way up to cockpit floor level. My 14 inches between 110 and 124 are still good no panic.

-on the aft face of 124, I placed another similar rectangle reinforcement.

So basically now at keel box area f110 is 3/4 inches thick and f124 is 1/2. Should be strong enough. By the way, once again thanks Kevin and Tim R for helping me understand how I should reinforce that area.

Kevlar frenzy

Not too clear on the pictures but I added strips of 300 grs twill Aramid fiber on the frames which had the bigger gaps with hull sides. In my case , f53.5 and 169.5.

Most of the builders had this problem, maybe not on the same frames, but many chose to "sister" the frames with ply reinforcements.

For the fun of working with a different composite, I went with Aramid. It is probably one of the toughest things around and I think it could handle the job of holding those frames were they belong. Dont forget that all existing space had been previously filled up with epoxy/microfiber/silica putty. It is strong as steal !

But I have to add that working with that Aramid is not easy....First of all it is really difficult to cut. I tried everything I had at hand but nothing worked. So after asking for some advices on the forum I bought myself a pair of those really heavy duty scissors wich can cut metal sheet. I figured they would work. And yes indeed those shears worked fine.

Second, it is hard to laminate. The fiber I got is not a tape, its a big roll. So that I had to cut the tapes myself and those slippery aramid fibers seem to have a mind of their own wandering all over the place. So i used the technique described by some (Peter Ross, TReiter) and saturated those cutted strips of epoxy resin on top of a sheet of paint drop plastic. Then took the whole thing , with plastic film and all, right on the frames /hull junction, and used my plastic squeege to
laminate the aramid strips, plastic film up. Took the excess resin out, pulled the loose fiber strings along the strip, and let it cured. The next morning I removed the plastic film (comes out so easily its a joy !) and the trick was done with minimal mess. I have to admit however, that this is definitely not the cleanest fiber work I have ever done.

Just a quick explanation here : although I am a first time boat builder, I have had some previous experience with resin (polyester) making surfboards during my years in college. Good memories. So I am not scared of that mess.