Vector - Core, Stringers & Floor Replacement

[KOMotion]

I have finished removing the floor, core and stringer system from my Vector. The floor and stringers were in decent shape but the core was completely rotten.

My questions are:

1. Should I reconstruct the core, stingers and floor the way it was built originally or is there a better design/method? I was not too impressed with the balsa lying over top of the plywood floor.

2. What is the best way to lay the new core back down? The guy I bought the foam core material from suggested putting a layer of mat down underneath the core to help hold the resin.

3. Can I use treated plywood or will that cause problems with adhesion to the fiberglass?


Your input is appreciated.

Kevin O

[ScottyG]

Kevin, I just finished recoreing and reflooring my Vector. I laid Klegecell 75 on top of a bed of 6oz bi-weave matt.I used cinder blocks and old car batteries to weigh down the new core and put in a small section at a time.I then covered the Klegecell with 24oz bi-weave matt.I replaced the keel beam with a prefab beam from west marine.I then replaced the floor with untreated non-marine douglas fir wood with 6oz matt on both sides.I reconstructed the core and keel beam to the same dimensions as the original and to answer your other question in no place does the Klegecell go over the new floor.I used West System epoxy for everything.It took about 6 gallons to do the job at about $100.per gallon and about $300 for fiberglass and another $200 for the pumps,additives,rollers,brushes,acetone etc.I am not saying this is the only way to do it as there are many but this is based from alot of opionions mostly from very nice people on this board.Just keep asking questions and don't rush it.Also go to the IHR and check out various peoples Hydrostream recores for ideas.BTW remember to support the pad,the steps and the chines while you have the core out until you glass the new one in.Scotty

[KOMotion]

ScottyG,

Please take a look at my cross section sketch attached.
This is how my floor was set into the boat.
Are you saying the your core didn't overlay the plywood floor like the area I have circled in red?
What does yours look like, it sounds like it's better.

Thanks,
Kevin O

[bulldogdaddy]

didn't realize there was that much wood in a h-stream. scotty you've come to the right place. some of the glass "gods" should be replying soon.

[Techno]

Whatever you do don't use treated wood. You want dry wood that is sealed and preferrably marine grade.
I used Klegecell for my floor and it has to span 4' width with nothing to help.
It's a bit of a pain to mount stuff to it though. It does cut the floor weight in half.

[Jeff_G]

there are a number of different ways to approach the job, both from materials and cost standpoint.

What I would recommend is to use klegacel or another foam. Make a paste of epoxy and collodial silica and embed the foam in it.

Clean the bottom of the boat and rough it up with a grinder. Spread the bedding compound (epoxy and silica) in a appox 1' X 1" area. Place a piece of foam in this bedding compound and then cut the foam into small blocks of 1 1/2" square. Firmly bed them until the bedding compound oozes up, then lightly spread it over the top of the foam with a squeege or putty knife. What you have done is made a minature "I" beam. This will make the bottom extremely strong and light. Only work with small sections at a time. After you have completed the bottom lay in some glass with epoxy resin. Do not use mat with epoxy unless it is made for use with epoxy.

For the floor use some exterior plywood and put a thin coat of epoxy on the back side. Then put your glass on the top side. If you want you can "bed" the floorboard to the stringers with the same putty you made to do the bottom.

Reletively easy, very strong and light. I recommend 1/2" foam.

To keep the bottom straight I laminate 4 pieces of 2X4 lumber, then take it to a woodworking shop or mill and have it trued in a planer. I support the bottom on this. After the bottom is done very little truing of the bottom is necessary.

Hope I didn't lose you. If you look at the balsa core you will see it too is probably made of small squares with a woven backing. Some manuf. used 1/4 or 3/8 plywood in 4" X 12" strips and simply glassed them in.

Let me know if I can help further.
You can probably do the whole job for under $300.

[H2Onut]

But it may help.

http://forums.screamandfly.com/forums/showthread.php?s=&threadid=8271&perpage=15&highlight=Vector&pagenumber=1

[ScottyG]

Kevin,My Balsa core ended at the plywood floor and did not go over the floor like in your drawing.(I guess Hydrostream changed some things from 78 to 84)So when I rebuilt I did not put Klegcell back over the new plywood floor in the area you circled. I did however put it in the area higher than that just before the gunwales and ended it right at the area you circled.Then I blended it together by cutting the edge of the Klegecell at a 45 degree angle and glassing over that.BTW,be sure to put in your new core to the same dimensions as the old one in this area as you do not want to interfere with the area where you will bond the floor to the boat.When you are done removing core sand down the whole area good and vacumn the dust out so you get a good bond and clean with acetone before glassing.Don't sand without putting the space suit and mask on otherwise you wil be miserable after. The message above this one details very nicely about cutting the Klegecell into smaller sections and glassing it in.Its all good advice.Scotty

[thumper]

hi Kevin -
If in fact your bottom looks like your drawing then you are the second to recore your boat. Pipkorn never made something like that. It would've cost too much in materials and would have not increased strength at all. Did your floor have definite lips in it where the balsa stopped that you could see through the carpet?
The above guys have very sound advice for replacing the core. Pick your coring material and then lay it with care. I made many mistakes when I recored my viper I wish I could have back. I think the key is don't leave any empty spaces, fill them in with the resin/lightening material mix and weigh them down to squeeze them for curing. Above all, don't rush it. Ask a lot of questions.
Walk slow and drink a lot of water I was told once. It holds true for a recoring project. Most of all, good luck!!

[Techno]

Never did a recore but wonder if it would be easier to use sand bags for the clamping weights?
Even if you don't buy sand, bags of dirt would seem to spread a load out nice and still be managable to move around.
Thinking along the lines of garbage bags filled with about 30#s, something that isn't going to kill you moving them around.
Stack several to increase weight if more than a bags weight is needed.
Seems to be better than scrounging for movable weights around the house.
Water would work too but is a bit more messy, maybe buckets but dry stuff seems safer.

I'm not sure I would use silica as a filler. I would check first but some of the other light weight fillers may work. Save weight if they can be used. Not saying they can be used but worth checking out. Thinking the foam only needs a good bond and not so much a structural thing, it's foam.

[Jeff_G]

Basically the foam is a filler material. The Collodial Silica increases the strength of the epoxy, it's density and saves weight. It is the "minature I beams" that are formed of the epoxy mixture between the squares of foam that give you the strength.

[KOMotion]

I picked up all my supplies at local boat builder. He gave me some core foam material that came in 2' x 4' sheets. It is pre-sliced into 2" x 2" squares with a thin mat on one side. Is this the kledgcel you guys are talking about?

He told me to lay down some resin and mat and press the foam with the mat side down into the resin/mat. Then follow up with the top layer. Do I have to put the top lay on before the lower layer cures?

How are you weighting the foam down without having your bricks or weights getting bonded to the foam?

[Dave S]

You can use a polly plastic tarp, the glass don't stick to it. Now for a question, how do we know when the core is bad? My vector (new) to me at least, seems to be in good shape, how can I tell without pulling a good boat apart?