New Centerboard

[oded kishony]

Greetings:

I'm hoping to get some collective wisdome from this august group. :)
I'm faced with the task of building a new centerboard for my Paceship PY26
The dimensions of the board are (roughly) 15" wide, 48" long and 1.5" thick
I'm thinking of fabricating the CB from this fiberglass sheet.

http://www1.mscdirect.com/CGI/NNSRIT?PMAKA=31983422

The hoped for advantages are:
greater ease of fabrication,
no issues of future water penetration,
no need to include additional weight,
ability to easily create a 'foil' section,
plenty of strength.

I'll create the foil section by cutting strips and epoxying then fairing the steps with epoxy.

What do you think, is it hair-brained or not?

Oded Kishony

[Coastal Cruiser]

Well, I may have missed the specs on it, but make sure that the glass in the board is more than just chopped matt.  You need some form of stranded fabric, or a woven product. I would also wonder about any warping if you are just attempting to use a flat sheet, and then build your foil up on it.

[CapnK]

Oded -

Now just who do you think you are calling "august"? >:( ;D

I'm with Coastal on this - you need to find out how it's constructed. If it's CSM, that would be a no-go for me, even as a core material, because as a centerboard it's gonna have a *lot* of force applied to it in multiple directions at once, and although it might never do it, I'd want a CB that I *knew* I'd tried to make so that it wasn't going to fail. CSM isn't the greatest at taking twisting forces. At any rate, this board is only 1/4" think, which means you'd be building up 1.25" of that 1.5" blade anyway - might as well make sure it's all woven.

This might help you - We used to make surfboard fins by laying up many sheets of cloth flat (onto a glass sheet - window glass). Once cured, we'd cut the fin shape out (using a template), then take a grinder to it to put the foil on it. When it got attached to the board, it also got wrapped in 2-3 additional layers of cloth which enveloped the whole shape of the fin. Perhaps you can adapt this method to what you need to do...

How are the factory-made boards constructed?

And a person you might want to talk to - Joel Santarone at Idasailor Marine. I worked with Joel to develop an aluminum/HDPE foiled rudder for Com-Pac 16/19/23's. He's probably undertaken a similar project to what you are considering at one point in time or another. Joel's a nice guy; it's been a couple years since I talked to him, so, if you do, tell him I said "Hello!", OK? :)

[captedteach]

I think that at 160.00 a sheet plus freight you would be into it for WAY more than its worth.  Once you figure in your time you'll have over 1000.00 in that project easily.  If you want to make a hollow foil I would look at aluminum use a 1/4 in sheet for the center and the ribs then skin the whole thing with 1/8 in sheet. Pivot points can be added with tubing - welded first to the center rib and then to the skins . Have it hard anodized or powder coated when finished then paint with barrier coat and anti fouling.

I would also call Joel at Idasailor Marine just to see if he has that on his list of availble products.  I sold a Hunter 23 rudder to a customer that Joel made - Life time warranty and a SOLID product. It may be that he will have something that is real close to what you need and will send it un drilled so that you can locate the hardware where you need it.

[oded kishony]

Hi Captedteach
>  I think that at 160.00 a sheet plus freight you would be into it for WAY more than its worth. <

I'll only need one panel and a bit of epoxy with filler. My purpose in choosing this method is for it's simplicity.  My planned method is to stack layers together (think topographical map) I'll cut the panels on a table saw, epoxy them together, fair the steps with epoxy filler and if I'm feeling ambitious wrap the whole thing in a layer of Dynel w/epoxy. Seems very straight forward and in keeping with the KISS philosophy. I can't see that amounting to $875 worth of labor.

I will contact Idasailor, I've heard they do good work. Thanks for the suggestion.

Oded Kishony ~~__/) ~~

[captedteach]

IF your demisions are 48x15x1.5 and a sheet is 48x48x.25 you will need at least two sheets to get the thickness(six layers the first two are 15in then two 12in - we are already at 54in)  Remember that you have to keep it symetrical -  so thats 320.00 plus freight. The silica for that much filling and fairing will be about 50.00 and at least a gallon of epoxy with hardner - I dont use epoxy in my repair work as it takes too long so I dont know the current cost but lets just say 100.00 so you are already at 470.00 and have not even broken the first jig saw blade or worn out the first grinding wheel.  I dont know what you value your time at but lets say 1/2 of my shop rate or 32.50/hr - Can you do this project in 15hrs working time? 

I have some sheet stock sorta like that I picked up to build a control house for a water well company - its pretty flimsy. I had to glass wooden ribs to it so it would stand up.  True that is not a bunch of pcs laminated together.

For a project like this I think I would at least use a marine ply core and shape with fabric just like a topo map but in reverse. Put the thinner strips down first so that the last layer is a complete skin or I would do it in structural foam like klegecell.  Look at some aircraft wing structures to see how those are built - nice and lite weight and very strong - the aluminum CB I mentioned in my first post would be built like this but it would work with other materials as well.

Doing projects like this is great but look at all the options before you dive into one. Sometimes building is not the best option.  Sometimes its the only option

My first choice would be to see if the part was available in the retail/wholesale market - if not then custom work comes into play.  This is coming from someone that does this stuff everyday - unless you talk to Adam and he will tell you I only work about five days a month. 

[oded kishony]

Hi Captedteach,

Thanks for your excellent input and invaluable, experienced advice.

>My first choice would be to see if the part was available in the retail/wholesale market - if not then custom work comes into play.  <

Excellent! I've already emailed Idasailor. Let's see what they got.
I've also emailed the fiberglass panel manufacturer for structural specs. (this is the most fun I've had this week ;-)

> IF your demisions are 48x15x1.5 and a sheet is 48x48x.25 you will need at least two sheets <

Here's the plan: one panel 15'x.25x48  two panels 10"x.25"x48" two panels* 5" x .25" x 48" *
total usage: 45" x  1.25" x 48"  Note that I maintained symmetry of foil shape.

*I'll make a template of the  NACA foil shape and decide on the final placements and dimensions
of the narrower panels.

I'll finish the last .25" by wrapping the whole shebang with a layer of  Dynel fg cloth and epoxy

I just finished reconstructing an anchor locker hatch using balsa core and dynel woven fg cloth .
A gallon of epoxy seems like a LOT of epoxy.

> Can you do this project in 15hrs working time?  <

I don't know. While the shop rate as a violinmaker is the same as yours, this is my hobby, it's how I relax. If  I were concerned about the cost, I'd hire a college student. I'm guessing it will take me about 10 hours to complete the job

I'll report back on what I hear from Idasailor and from the fiberglass manufacturer. If I decide to go ahead with this project using fg panels, then I'm going to document it and it will be posted on the Paceship web site.

cheers,
Oded Kishony  ~~ __/)  ~~

[Coastal Cruiser]

Hum, 15 hours for a rough cut, custom fabricated, shaped and finished board, if you have never done something like this before?  And what if there is a boomerang in it? Hum? And do you have a place and all of the materials readily avaliable , locally, to do this yourself? Hum, since I do not know anything about past, present, and future talents, I say ......Hum............Yep, Hummmmm....Now to the sidelines in Detroit for an evening with the commercial advertisers...

[oded kishony]

>And what if there is a boomerang in it?<

BOOMERANG????  :o  (explain boomerang please)

>And do you have a place and all of the materials readily avaliable , locally, to do this yourself?  <

I have a sophisticated workshop where I build violins, violas, and cellos- but I wouldn't dream of building this in there  ;)

I know,  I'm also very skeptical-notice that I haven't launched into this project-so far I've just flapped my lips alot.

Oded

[Coastal Cruiser]

With upmost respect to the talents of a violin maker, my words were more food for thought and yes also flapping my lips[fingers] as is most on forums when discussing these custom projects. The best part of these boards is kicking around thoughts for all to read hopefully for future reference if the need arises.

It has been my experience with centerboards, even factory built ones that require repair or rebuilds, getting it the same size, and keeping the new one or repaired on moving in the same slot, can be an issue. IN laminating wood, and building up layers of glass, a set can take place if you work on a surface that is not a flat mold,  one that is true in all four corners, no different than a house fondation.  Even a sheet of thick plywood, layed on a table or a set of horses, can have its own preformed shape in it, that must be addressed before using it as a working platform.

If not, a cupping or boomerang affect, I call it, can make you  :'( and come back to bite you after you finish this project.

The first thing that I would do is to sight down the existing one, of possible, checking the movement, aliginment and the thicknesses, as it applies to slot, too. When folks do a new one, from an old one, in some cases even the slightest over sized build, stemming from some of the glass applied, and layers of buildups on the edges, can create some issues after the fact, especially in painted ones, that gets barrier coats and heavy  bottom paints.

Respectively, keep this in mind, if this is your first attempt. Most of this maybe elementary to most, but given the initial posting, I felt that I would just add to the construtive posts that showed up after my original reply to you. If I can answer anything else, throw it at me, and will attempt to flap my lips[fingers] again.

[oded kishony]

Greetings Coastal Cruiser,

Having read your past postings with admiration, I recognize that you are the maestro and I, the sniveling, know it all, newbie. I appreciate your comments. I hope my little adventure won't be TOO entertaining as once when attempting  to dock with the wind on my ass. Ahh yes, we all had a good laugh........no damage except for a bruised ego.

I noticed that the present (damaged) centerboard is scuffed on the sides. I'll have to take a few more measurements and think about perhaps keeping the board just a bit undersized.

My other consideration is with the pivot. What do you think about having  several sheets of thin delrin or high density plastic as spacers at the sides of the pivot point.  I'd like to limit lateral movement of the board there to a minimum. The spacers would be outboard of the centerboard and would snug up the board in the slot while also providing a slick surface for the board to rotate on. Any thoughts? Is this just  'mouse milk'  :D   (too little to bother with)

Oded

[Coastal Cruiser]

Okay, nuff of that Maestro stuff. ;)  You ain't heard me sing, or heard me play anything .  And if you did....  :o  Now my kids? Now thats another story. We had a slight defect in my son's last trombone. The dang thing cross bred with a trumpet and still was able to play it.

;D



Now speaking about that centerboard, you bring up an interesting comment. You say a few scratches? Tell me more about the present one, and I will give you a bit more lip[finger] service.  I am by no ways an expert here for your requirement, but willing to listen. As far as the washer deal, accessability and pivot pin may come into play, too, if you are getting some banging noise. What type of pin, slop and all that Jazz...

[oded kishony]

Hi,

I got a response from Idasailor for a custom centerboard. Cost is about $600 which seems very reasonable
They plan to  build it in solid hdpe.
(high density poly eltheylene???)
What would you do?

Oded Kishony

[Coastal Cruiser]

Its hard for me to comment on the quote for your new board since I have little to no experience with using the product. I do know that there are some using it for centerboards, but cannot attest that for your application it will be a workable job. I just don't know.

But tell me again about your present board, condition, any pictures and related thoughts on what has lead you to believe that your board, in your opinion, is not repairable, or workable as in its present state. I may have missed it.

[oded kishony]

Hi Coastal ( ok if we're on a first name basis ?  ;) )

The present board barely exists, It is just a slab of plywood that had a cutout at the bottom where concrete had been inserted for weight. It was not foil shaped. The bottom had sheared off because the shackle had given way and there was no way to raise the board. Idasailor got the specs of the original board which are larger than the board that was on the boat (which obviously was not original) If anyone is interested in these specs I can email them but they are too large to add as an attachment.

Oded Kishony

[captedteach]

I would buy the board - It will be solid so you can drill where you need to add hardware. The Hunter 23 we have an Ida  rudder on is PUSHED all the time and have had zero complaints with the product. Its also maint. free - Just pressure wash it at the end of the season.  When its time for blades for the Gemini I will be calling Joel - maybe for my Harstil too

[oded kishony]

Thanks to all who offered advice. I decided to purchase the centerboard from Idasailor. I've been impressed with their service so far and I'm looking forward to installing their centerboard. I'll keep you all informed as things progress.

Thanks again
Oded Kishony ~~ __/) ~~