Farrier TrailerTri 720 Centerboard lamination

Hi everyone! New user here, longtime boater.
We bought a Farrier Trailer Tri 720 last summer and broke the centerboard. I'm currently working on a new one. I'm going
foam core. I'm not sure what kind of foam I have, it came from a windmill blade factory. I think it is PVC, could be high density, not sure how to tell.
I can't afford carbon fiber but fiberglass and maybe a little bit of aramid or Kevlar are okay. A fellow TrailerTri 720 owner was able to give me a layup schedule for carbon with foam core as follows:

7 layers of 300gm uni sandwiched between two layers of 200gm biax with an additional layer on the head and a strip down the leading edge. The uni was 100mm wide and staggered by 120mm steps from the longest to the shortest.

What would you guys recommend for a layup schedule with adequate or similar strength using fiberglass? I've never worked with fiberglass but I have an uncle who used to make surfboards.

I have enough core material for 1 mulligan lol. But I hope it becomes a spare. We're holding off on using it until the first one survives a couple years.
Any book or resource recommendation is welcome as well!
Thanks for your help!

 

There is a dedicated TT group on groups.io

TrailerTris@FCT.groups.io | Topics https://fct.groups.io/g/TrailerTris/topics

Generally converting from carbon to glass double the weights.

The TT plans are in the files section on the TT group so you can download them and keep them for future reference.

Good luck.

 

I am a member there and I have those plans. But they only cover making the board out of plywood core. Does anyone have resources to suggest for determining a layup schedule? Or is it all best guess?

 

A laminate schedule of an f24 or similar will do.
Fibreglass for the biax is fine, I wouldn’t sub out the carbon. I don’t see the savings on a few metres of carbon as having a cost benefit unless you are also going cheap with polyester resin ?

 

Thanks That's I great idea. I'll track a lamination schedule down for an f24.

I'm in Nova Scotia, Canada and as far as I can tell carbon of any kind is about $60 - $70 a yard whereas fiberglass tends to be under 20. I estimated that the carbon layup schedule I have would cost $1300 Cad before tax. But I could be wrong.

I have poly but I was going to use west system to try and get the best result possible. I'm open to recommendations there as well.

Is there a cheap China supplier of carbon that people use?

 

Soller Composites UNI https://www.sollercomposites.com/UNI.html

 

There is a source in New Hampshire. Business is named Soller Composites. I have ordered several types & yards of CF cloth for testing (nothing more) for my refit. However, the quality delivered is excellent. Their prices are very affordable, even with Canadian import tax. Well below your stated pricing... I would give them a call to discuss further, as they are a wealth of info and often has partial rolls that sometimes don't get posted on the website.

If you go CF, then you might graduate to WS or even Pro-Set. Just depends on your need for documentation of completed repairs. My NA keeps 'strongly recommending' for me to make the jump to Pro-Set as well...

There is a retired Corning Engineer in my marina. He has on more than one occasion filled me with terror about the proliferation of marginal (and worse) CF coming out of non-standard sources. I would be wary of buying inexpensive CF cloth from overseas. To be fair, he told me that this 'less than adequate' cloth first started coming out of Eastern Europe. Over time, it has then become more centralized (of course) now in certain Asian countries...

Good Luck! - Ogre

 

Quick on the draw!

 

I have no experience buying from them as I am in Western Australia.
Use your epoxy it complements the carbons properties way better than the polyester.

 

Weigh the foam core and take a picture of it and measure it with a caliper to determine density and type.

Isn't there a practical limit on the thickness of the centerboard?

Is the lift assisted, so is there any weight restriction based on the lifting?

It seems like these constraints are to be considered from what little I know about sailing. My brother has a centerboard sailing boat and his trunk got a bit swollen and affected the board. Same thing if a board is too big no?

Determining what core you have is pretty important to plan the layup and determine suitability. But weight of panel and measurement give density.

The biggest issue would be making sure it doesn't get too fat in hand layup. This will require either vacuum or careful work. But I'd want to bag it for the glass to make the edges well. Probably one side at a time, then radius the backside edges after the other side is stiff(er), but you may still want to support the other side if bagging.

 

A common way to build boards is to use foam as a core, but to use a hardwood shear web in the fattest part of the foil. It doesn't have to go all the way to the tip, but should be wide enough that all the uni carbon can laminate onto it (3" or 4" wide).
The shear web with laminate on both sides takes virtually all of the side loads, so the rest of the foil can be foam & glass.
Pro-Set is very strong, but you have to be more careful measuring when mixing as the higher strength epoxies have less room for error on mixing ratios. I use Pro-Set 125/226.