Over built or waste of materail?

[MR nova @#25]

I have the diagram for glassing in a floor that I found on this forum. 1 layer of CSM on the underside, 3 layers of CSM on the topside plus the 1708 3in Tabs. if I apply 2 layers of CSM to the topside and a layer of 1708, Would I get a lot more strength from the 1708, or just add more weight to the boat with no significant structural gain? Burn more fuel..

Thanks again

 

[Mud Puppy]

Re: Over built or waste of materail?

The CSM holds more resin than fiberglass cloth but has no structural strength. 1708 is "bi-axial" meaning it is two types of material stitched together; 17 oz glass woven roving and 08 oz CSM. Woven roving is different than fiberglass cloth as fiberglass cloth is twisted fibers while the woven roving are straight stands in groups and interlaced together in a "weave" pattern thus giving you structural strength.

You have to seal the bottom and edges and resin alone will not be a thick enough layer so the 1 layer of 1.5oz CSM will be sufficient resin content to do so and no need to do more there. DO HOWEVER insure the edges are sealed when making but joints against other plywood.

Usually joints along the hull have sufficient "sealing" due to peanut butter, but I would seal those just as a precaution. It is the resin that makes it water tight, the roving that gives it strength.

 

[DeepBlue2010]

Re: Over built or waste of materail?

In general, you get more strenght out of 1708 than CSM. Few questions..

What kind of boat you are working with?
What type of wood you are using for the deck (floor)?
What is the width and lengh of the deck?
Is it fully supported under the deck or it will span unsupported areas?
If so, what are the dimensions of the largest unsupported area?

 

[Woodonglass]

Re: Over built or waste of materail?

CSM is required with Poly resin to bind the resin together. With out it the resin is very brittle and will crack and break and allow water intrusion. For your deck top, it all depends on what your final finish will be. If you're gelcoating or painting then CSM with the 1708 tabbings to the hull will be fine. No need for the 1708 full layers. If carpeting I'd go two layers of CSM and finish with a layer of 6oz fabric. This will provide adequate strength and waterproofing.

 

[Auger01]

Re: Over built or waste of materail?

Biaxial in reference to FG cloth usually refers to the orentation of the cloth i.e. the fibers are at a 90 degree relation to each other.

 

[MR nova @#25]

Re: Over built or waste of materail?

1976 Wellcraft nova 250 offshore. Every piece of wood form the cabin to the transom, has or is being replaced. It has 3 floor section 6 1/2 ft. x4ft 3/4 Ply. Where the pedestal seat mount the plywood was doubled under the floor. The wood was coated in polyester, Sat for about 4days than covered with CSM ( Not in the boat)
The stringers run almost 12ft before they touch the bulkhead forward of the engine box. I added staggered bulkheads every 4ft ( beefing up the motors a little and adding a hardtop) a little more stiffness.

 

[MR nova @#25]

Re: Over built or waste of materail?

Gelcote yes carpet no.

 

[ondarvr]

Re: Over built or waste of materail?

Biax refers to the direction of the fibers, the true meaning is +- 45* degrees on the role, these fibers are stitched together so they can be used in the best fashion for strength.

I wouldn't use 3 layers of CSM, it will just add weight and cost, if you want to use the 1708 just use 1 layer of CSM under it.

 

[ondarvr]

Re: Over built or waste of materail?

The 1708 will leave a pattern that can easily be seen on the surface even with a layer of gel coat on it, this is why in some cases CSM or cloth is used as the top layer. I used a 2408 0-90* fabric on mine and used the pattern as the nonskid.

 

[MR nova @#25]

Re: Over built or waste of materail?

good copy

 

[MR nova @#25]

Re: Over built or waste of materail?

I'm planning to add some type of non skid, maybe sand in the gelcote?

 

[Woodonglass]

Re: Over built or waste of materail?

Yup sand will work, or they make a non skid additive...http://www.bottompaintstore.com/nonskid-additive-for-gelcoat-p-10376.html

 

[MR nova @#25]

Re: Over built or waste of materail?

I'm concerned because, when I cut the old floor out. I was amazed at the amount of Woven roven used to make the floor 1/4 thick glass and resin Top and underside of the floor.... I'm all ears

 

[GT1000000]

Re: Over built or waste of materail?

I went about it a bit differently...
Before I installed my deck/sole sections, I sealed everything up, top & bottom, with a layer of CSM...then I just PB'd & tabbed in the sections with CSM...
That's it...I haven't done any additional 1708 tabbing at this point, since there is a lot of super structure that is going in.
Once its all in place, any points between the sole and hull that have not received any additional 1708 tabbing, will get some small sections applied to "complete the bond"...
Since I am building structure on top of that, and will be tabbing bulkheads to it, the actual area of exposed sole becomes less and less...
The only places I might add a layer of 1708 to, are those area that will need the added wear protection, such as the bottom of the storage lockers, where the final finish will most likely be some kind of paint/bilgecote...and the actual seating area and casting decks, which will see all the foot traffic and hopefully fish blood and guts...
Then again I have probably overbuilt my boat to such a degree that I will need a long, direct hose to the fuel station and snails may swim faster than it, but at least I will know it is strong...
Just a half penny's worth for thought...

 

[MR nova @#25]

Re: Over built or waste of materail?

Thanks

 

[MR nova @#25]

Re: Over built or waste of materail?

One guy told me: CSM,1708,CSM,1708. 2 layers of finished CSM or Veiling..
decision decision

 

[gm280]

Re: Over built or waste of materail?

Just my opinion!

Is there seriously anything wrong with over building...anything? I look at it this way, the little extra weight added by applying resin and/or extra material is meniscal in the strengthen and longevity it will then have. So if you, for chance, loose a little top-end speed because of extra strengthen and weight, will it seriously matter? I've never caught any fish at 60 MPH personally... Knowing you did it right is more satisfaction then a mile per hour extra speed in my book... But that is just me and my 1.5 cents worth (I don't have the full two cents because I spent it on extra building material)! :facepalm:

 

[Woodonglass]

Re: Over built or waste of materail?

Yes, overbuilding will Ruin our economy and cause us to have another 1920's economic depression!!!! We'll all have to sell our boats and fish from the bank with willow branches and safety pins!!!

 

[gm280]

Re: Over built or waste of materail?

Yes, overbuilding will Ruin our economy and cause us to have another 1920's economic depression!!!! We'll all have to sell our boats and fish from the bank with willow branches and safety pins!!!

WOG, do those willow branches and safety pins really work? I like bamboo and paper clips myself... :watermelon:

 

[Woodonglass]

Re: Over built or waste of materail?

Caught my first fish with one!!!! Spring Creek, 5 yrs old. Red Earth worm for bait. 4" perch.