I am about to glue a stringer into a Hurricane.
Which adhesive do you recommend ?
5200 - is actually a sealant, I hear it is quite difficult to work with
two component foam
regular epoxy
epoxy with G/flex
epoxy with micro baloons and silica\
It's the regular 1 inch Dow styrofoam, blue.
Submitted by eckhart on Thu, 02/07/2008 - 8:19pm
stay away from 5200.
Karel uses A/B foam for both the deck and hull, Kai uses an epoxy putty and a few peaces of glass on the hull and foams the deck. I personally attach the deck to the hull with fiberglass tape along the entire length of the stringer, and foam the top. I suggest foaming only the top because the A/B foam has the tendency to print through pretty badly when your boat heats up, and i always try to keep the hulls as clean as possible. I'm sure it has no effect on drag or anything I'm just a perfectionist.
#1 Thu, 02/07/2008 - 8:35pm
hi waterboy808, thanks for your comments.
On the Hurricane the cockpit section of the hull has been removed; the stringer will run from iaku to iaku.
I have not worked with foam, but I do not see a good way to apply the foam in this situation - I have to 'hinge' the stringer into position.
How about epoxy putty top and bottom ? What consistency ? Rather micro baloon or rather silica ? I decided not to add G flex, as I am not sure that it would make a difference in case of a major hit.
Regarding glass at the hull, as far as what I have read: either glass it all, or don't glass, iow the way you do it.
How wide a gap to fill do you usually have between hull/deck and the stringer ? A nickle, flat ?
#2 Thu, 02/07/2008 - 9:44pm
Most boat builders would use foam in this situation…..but using a putty is still an option.
If you only have access one section and need to attach a stringer that has become attached in a section you can not reach foam is definitely the best option.
1. First tape the stringer down where you can and get it sitting the way you want.
2. The blow or vacuum any debris or material that might be in the bonding area.
3. Mix your foam and pour where you need it, if you can reach an area just tilt the boat so the foam runs to where you need it, the A/b mixture is pretty thick so it will cover along the whole area it runs and quickly rise. Securing the stringer in place. I suggest you do this in two passes one for each side.
Securing the deck can be a little more complex
1. First you need to dry fit the deck on top of the foam and make sure it fits. I suggest using dabs of chalk from a chalk line refill to tell you where you are high. Don’t shave to much off at one time, it is ok to test fit it several times.
2. Once it is fitting good shave/cut a groove along the top of the stringer….there is a very easy way to do this with a common household tool…… but I cant give away all of my boat building secrets.
3. Once you have your groove cut, mix your foam pour down the groove and secure the deck with anything to hold it down probably lots and lots of tape.
A few tips for working with A/b foam
1. It rises very quickly you probably have only about 20-30 seconds of working time once you mix it completely…. so work fast and have everything ready before you mix it.
2. If you want to slow it down a little cool your fridge or a vat of ice water( the separate parts of course).
3. Always use a new cup to mix it in , this foam makes a mess and trying to mix in an old cup is hard an only slows you down.
4. Make sure you mix it at 50/50 it does not have to be perfect but the closer the better. I always poured part A and B into individual clear cups and made sure there were the same then I would pour them into a third larger cup to mix and pour.
It sounds to me like foam is your best bet in this situation; I forgot to mention use the technique I talked about in the first part to secure the deck half where you have not removed the deck.
A few notes on glassing since you asked… I feel the information on either all or none is incorrect. Some builder putty the hull stringer in place and just tag it every 2 feet or so with a strip of wet glass. While I do not agree with this method 100% I feel that a little glass is better then none at all. You see a lot of times putty mixtures can become brittle or even weak and a little glass keeps the stringer bonded to the hull in at least some places, and if a small section does break loose, the glass should keep the entire stringer break breaking loose and help to minimize the delam of the entire thing.
As for the putty I would recommend a peanut butter like consistency. There are several fillers you can use to achieve this. They are Aerosil, Glass bubbles, and Microcell.
Aerosil is the strongest of them all, but will suck up a lot of resin, be heavy, hard to mix and brittle. Glass bubbles and microcell are both faring filler designed for high build up heat control, and easy of sanding. This said almost all of the Hawaii builder use a combination of micro cell for our bulking up and aerosi to get the last bit of thickening and make the putty stand on itself/cling to vertical surfaces. I’m sure there will be some people who disagree with me, but I would likely go with a mixture of 80% glass bubbles or microcell and 20% aerosil, this should give you a good combination of strength, flexibility, and weight.
As for gap to fill I would say between an eight and a quarter inch, make sure not to squeeze all your putty out . Any ways I hope this makes sense…. I apologize for the numerous spelling and grammar mistakes… It is 1:30 in the morning and I still have 3 cases in contract law to finish before tomorrow, plus I’m kinda on a caffeine high… any ways I hope this helps…
#3 Thu, 02/07/2008 - 11:36pm
Thank you, great and helpful advice.
I looked at Karel's open hull in his shop mshowing the solution with the foam.
The groove seems a way to do it.
I'd probably also use glass as I have a boat with a lose stringer that slaps around.
I am planning to pour a thin, 1 inch wide 'socket' unto the centerline of the hull with epoxy to take away the radius, then putty the stringer into place, finally partailly reinforce with glass.
For the deck I am undecided; probably putty. Maybe use a ziplock bag, fill it with putty, cut off a corner and use that as a 'gun'.
When putting the cockpit section back unto the hull, I guess I have to use foam, or very stiff putty.
I determine the distance by setting up little soft clay cones that are being pressed down when I put on the part.
#4 Fri, 02/08/2008 - 8:47am
Be careful where you use AB foam, in very hot conditions apart from the the print through effect that waterboy mentioned, the foam can soften the resin in the hull and the keel line can "oil-can" (deformed surface) either side of the stringer, especially if this area has little curvature.
Should be ok on the Hurricane as it has Divinycell core, mostly happens to vac bagged coremat boats where the core is resin saturated. I have seen the both hull sides the entire stringer length buckle after very hot days where the foam is in contact with the inside hull surface. (can post a pic if you like)
I would use seam bond on the stringer bottom and ab foam on the top, with the slot waterboy mentioned. The trick with foam, is to cover a large surface area for strength and prepare the surface to be bonded.
Hope this helps.
Cheers rambo
#5 Fri, 02/08/2008 - 9:00pm
This Hurricane seems to have a 2mm coremat, is that Divinycell ?
The foam sounds good, but I am hesitant. I would have to apply the foam just before I set the deck back into place.
30 sec working time to get the deck into perfect position and pressed down on the seems - that's where I cut it - is very short.
Putty seems also far from ideal. It has a much longer working time.
How much would it matter if the stringer would not be perfectly attached to the deck in the footwell area, but good everywhere else - that's what I foresee happening - ? Would that be acceptable ?
BTW, Rambo, does your Pegasus meanwhile outshine your Hurricane ?
#6 Fri, 02/08/2008 - 10:05pm
Is your Hurricane the early Malaysian model? I'm sure they were coremat deck and Divinycell hull. Is the hull core pink colour? Does the deck flex easy compared to the hull?
Peggie and Huri are brother and sister, both get paddled regular and i love their differences.
The hot days i mentioned above were not the day the foam was poured, but 12 months later.
Let's know how the cockpit/rudder/iako position change goes. Divine or Disaster.
Cheers Rambo
#7 Sat, 02/09/2008 - 10:45am
Green hull, very strong deck actually, hardly flexes at all. The footwell was all glass.
I figured you would like both boats, who wouldn't ?
The repair is coming together well; the performance will be what counts.
Next week .... must be divine, no choice.
I obtained some G/flex; will try it to attach the footwells to the hull; may be a good choice to drill the hole for the venturi drain.
#8 Sat, 02/09/2008 - 8:52pm