I have a 2004 F18 I am re-assembling and would like a stiff boat, but want to be able to break it down again ?
any recommendations what to bed the beams with ?
also, there is a small bit of pitting in the beams where they sit in the hull sockets, how would you treat this corrosion ?
appreciate the help

From: http://www.ahpc.com.au/PDF/VIPER%20Tuning%20Guide.pdf

Hope it helps.

Reseating Beam Pads
After years of use the contact between the beam and the beam pad can deteriorate, resulting in reduced platform stiffness. To reseat your pads you will need the following: White Gelcoat, masking tape, mould release wax, sandpaper, acetone and a 50mm paintbrush.

Follow these steps (do one beam at a time so that you have enough time before the Gelcoat gels):

1. Remove the beam by undoing the beam bots and pulling the beam out.
2. Briefly sand the beam pad to rough the surface and thoroughly clean beam and beam pad with solvent.
3. Wax the beam anywhere it touches the beam pad or gelcoat might touch it (follow the waxing
   instructions on the packaging).
4. Mask up the edge and area around the beam pad where you don’t want gelcoat to be
5. Mix gelcoat and brush a 2mm thick layer onto the beam pad leaving a 10mm gap around the bolt holes
6. Bolt the beam back into place before gelcoat cures
7. Clean off any excess gelcoat with acetone
8. Repeat on other beam

By waxing the beams you should be able to remove them if you need to, however they will be quite stiff to do so.

instead of gelcoat, I used the West System Six10 pre-thickened epoxy.

Worked great.

Chances are you will need a thicker layer than 2mm for a Nacra hull socket. I've had one socket on a Nacra 20 require over a cup of resin to fill the voids in it. I've done about 6 or 7 various Nacra beams including your F18 model. Seating the beams does make a noticeable difference the the boat stiffness. You can use gelcoat or thickened epoxy to seat the beams. The gelcoat is nice in that when some squeezes out the edges, it should match the color of the boat and won't stand out - you don't need to be as cautious with it. However, I've used thickened epoxy on all the beams I've set previously but will probably switch to gelcoat on the next set I do. I first use clay to make a few "snakes" and use this to wrap around the beam bolt holes to prevent any adhesive from making it's way into the threads there. The clay will compress and make a dam when you snug up the beam. I also put a clay snake around the lower exterior sides of the socket to keep anything from oozing out where I don't want it to.

The waxed beam process is the same as mentioned previously and works to let the beam release. Use a good automotive carnuba based or specific mold release wax.

I thicken epoxy with cabosil (fumed silica) to a creamy, sour cream-like, thickness and pour it in the hull socket and work it around a little. The gelcoat should work in the same manner. Then I set the waxed beams in place and snug up the bolts...almost tight but not quite. Sop up the excess resin/gelcoat as it squeezes out (use denatured alcohol to clean up the epoxy, use acetone for gelcoat). I let it kick like this, periodically checking and cleaning up weeping resin, before tightening up the bolts the rest of the way.

PS - DO NOT use 3M 5200 as a seating compound. Besides not being a rigid material, I helped a friend try to remove a beam that someone had set this way...after trying everything for two weeks, he finally got it loose but not after some significant fiberglass damage to the beam socket and deck.

I recently reseated my I-20 beams exactly as Jake described. It worked out great! Allow me to add this suggestion to it. Once the beams are off and all is clean and ready to go, get some blue painters tape and newspaper and mask off the area on the inside and outside of each hull where the beam will sit. No matter how much cleaning you do as the mixture oozes out, it seams like it never stops. Of course I put it in kind of heavy. Just before it really hardens up tight, remove the tape/paper and taking a sharp knife, dress and trim any excess that leaked out.


Good luck

Forrest
I-20
USA-675
Hernando

A choice of gel coat or epoxy is not the big issue. That is whether you want to use polyester or epoxy. Gel coat is just thickened polyester with a pigment.

I used the West Systems Flex Epoxy, thickened with colloidal silica, last time and it worked great!

Make sure to clean and rough sand the area you want the material to adhere to.

I tape and cover where I do not want product to end up, including all the way to the bottom of the boat. It can get a bit messy the first time, as you will probably mix too much material.

Put wax, I use HiTemp Mold release (because I have it), in the thread holes as well as waxing the bolts. Be patient and put several coats of wax on the beams, waiting for them to dry in between and buff each time. I like to make sure with about 7 applications. This will make sure it is all covered.

Make all level and get ready with a tape measure to use crosswise. May be issues, but I have not had any with F18s.

After reapplying the beams snug the bolts down pretty good but you do not need to crank until you hear cracking. The filler will be your new bed.

Caution should be made if you think there will be closing around the beam (negative draft). Keep in mind that one day you will want to take the beam off, so it has to be able to release.

Have a fun time with it you will like the results,
Dan

My new (to me) F18 has gelcoat seating the beams and it seems to have worked very well...I didn't perform the task on this particular boat though. You also don't have to worry about it yellowing in the sun like epoxy...rather...any tiny bit of residual epoxy that may be left on the deck/side of the boat.

I've done a few of these. Some of things to add to the other advice.

Use west system 6-10 and have two tubes on hand. This stuff will give almost an hour before it starts to gel. Important to let the boat cure for at least a week before moving it.

I don't use a dam around the holes. I let the epoxy squeeze in there to fill any gap between the bolt and the hole in the beam. I will do a circle of epoxy around the bolt hole about a half inch away from the hole so the amount that gets in there is not excessive.

Before starting this I put the boat on the ground on a couple 2x4's or 4x4's that are a little wider than the boat, spaced far enough apart so the hulls are stable but don't touch the ground. Get a long level 4ft min. Remove the tramp. Loosen the dolphin striker. Check the level of the front and rear beams. Move the 2x4's fore /aft at the corners until both beams are level. It helps to do this on fairly level ground. You can check squareness of the boat by measuring front outside bolt to outside rear bolt on opposite side. Measure both ways see if they're the same.


Tape the beams and hulls leaving a small gap 1/8". Pull one beam at a time and sand the beds and wax the beams. I've used pva on some boats instead of wax. With pva I spray a couple very light coats.

Coat the bolts with Tef-Gel. I use about half the tube of 6-10 per bed. For some boats this may be excessive but for some it may not be enough. Keep in mind the tube of 6-10 is not as full as it appears. The piston is almost half the length of the tube. The tube will put out a 1/4" bead for about 20'. If your hull is a foot wide and you lay a 1/4" bead every 1/2" across the bed you'll be using 1 tube per beam.

Install the beams and tighten till the bolts are snug. Check level of the beams again. Make sure they are both level. Tighten the bolts a little more. Clean up and leave it alone for a week. Then tighten the bolts the rest of the way. Don't forget the dolphin striker.

Understand, most epoxys cure to about 90% in a week, 99% in a month. It's a waste of time and money to do this if you can't let it sit for a week.

I don't understand why you don't just spray PVA on the beams. It would take about 10 seconds to spray with PVA. Some people just like to work harder I guess.

I have used 'wax paper' taped to beam, but it would not be perfect as PVA.

I did the same with my N20.

Because PVA adds thickness which results in a not-as-tight fit as possible after it dissolves away. The wax works just fine. A semi-firm tap with a rubber mallet and the beams will release perfectly with a coat or two of wax.

Mike (the other Mike), I'm not sure I see the point of leveling the beams or even loosening the dolphin striker. I will take an "X" measurement on the boat to check squareness and try to do a little to square it up if it's out much...but you're not moving it much at all since the beam bolts are threaded into the hull. You have only the minimal amount of slop available in the beam through holes for the long bolt anyway..so most correction you put on it is just going to spring back after you release it anyway. Canted hulls introduce another level of difficulty (not the case with this F18 in question).

thanks for the advice, will do

thanks for the advice, will do

I've seen boats that when you lift one bow the other won't move until the one your lifting is 5"s in the air. If you don't start with the beams level to each other then you risk gluing the boat in a racked position.

On a modern well built boat some of that might not be needed but if someone has me do it then I'm going to go for best result possible. Loosening the striker lets the beam flatten out and makes it easier to get a level on it. Also not a bad time to take the striker apart and service it.

On a older boat that's never had the beams set it's very possible to find it out of square. Not much but I have been able to move them into position. Add to that 5" bolts in a 1/2" aluminum plate with worn threads. They move around.

One more thing about using gel coat. It shrinks quite a bit so I don't see it being the best stuff to use.

..... tell them that you really love them and you will respect them in the morning!

A bottle of red wine always worked well for me!

-sorry - couldn't resist-

A nice dinner and a show. Tell them your looking for a long term relationship. Never tell them you plan on using them and another beam at the same time, or you plan on sharing with your crew.

Absolutely never tell them you want to charter them out for cash.

or that you'll double- or triple-stack them

I have used PVA (very easy) and also wax paper both work great . i also use gelcoat not epoxy but either one should do just fine