Fiberglas work on a P26

[Jonathan Boright]

Greeting all, 

I have 3 Fiberglas tasks in front of me and this is my first time working with it.

The tasks are 

• Repair damage to the rudder.
• Repair/reinforce the transom
• re-core the cockpit sole

I have questions about materials and techniques related to each task, but in this post I'll start with the easiest, the rudder. Other posts for the other jobs are sure to follow.  

But first, quick questions about materials. I'm going with epoxy resin for these jobs, primarily (from what I understand from the school of youtube) because epoxy resin creates stronger secondary bonds with existing material... which is what I'm doing. Feel free to re-educate me if I'm wrong on this choice.

Banged up rudder:

Before I owned her, there was a motor mount bolted to the transom. At some point, it failed and the Yamaha 9.9 outboard was dropped onto the rudder (swung by the battery and fuel line perhaps?) ... causing a number of nicks, dings, and a chunk taken from the trailing edge. 

  

            

Most of the damage is small and shallow, some getting into the Fiberglas, others just into the gelcoat. The biggest hole is the notch taken out of the trailing edge of the rudder, roughly triangular about 2" wide (along the edge of the rudder) and 1" deep at the deepest.  My plan here is to go with West System products... and this is my understanding of the steps:  

1. Sand off the ablative (blue) paint. Q: how far beyond the damage do I need to go?  
2. Sand/grind the damaged areas to remove any loose material 
3. Wipe/clean the area with acetone
4. Wet the area with a coat of un-thickened epoxy (West System 105 and 206), making sure to get into all the crevices.
5. Mix up some thickened epoxy using one of the West System adhesive fillers.   Q:  Which one? Perhaps 404 (high-density) would be be the right choice? 
6. Apply the thickened epoxy to the damaged areas once the un-thickened coat is tacky but not totally cured.  Q: Will the thickened epoxy be strong enough to fill the gap in the trailing edge? or should I add some fibers (FG mat perhaps)  in there too?  Or perhaps a layer of FG mat over the top of the thickened epoxy fill?
7. Let it cure totally and then wash it with soap and water to remove the waxy film (amene blush?)
8. Sand it smooth and clean it with acetone.
9. Mix up a batch of epoxy with a fairing compound added  (WS 407 or 410 perhaps?) and apply it to the area.  Q: do I need to add another layer of unthickened epoxy here first before the fairing?
10. Repeat 8 and 9 until I'm satisfied with the smoothness...

Here the plan gets more vague... do I add a final layer of unthickened epoxy as a top layer? What product(s) do I use on top of the epoxy layers? Paint or gelcoat? I think that what I see as I sand away is gelcoat underneath the ablative blue paint. Should I stick with gelcoat here or use something else to cover?

I think I'll leave this missive here and start other threads for the cockpit sole and transom work... as it arises

Thanks all!

J

[Dave Cole]

Your rudder is banged up, but its really all cosmetic from what I can see.

Basically you need to grind down to fiberglass.  Through any gell coat.  Grind it back a few inches so you can fill and fair without going over bottom paint.

Then apply some epoxy, then thickened epoxy.  

Smooth and fair as much as you want, then paint.  

Keep in mind this is not a structural repair. 

Ive used various epoxies from different companies.  West is good but mixing 5:1 is tricky.  I prefer 2:1 epoxy as the mixing is much simpler.

Ive been using Raka epoxy for the last 6+ years and it works very well.  Their non blushing epoxy kits are excellent.  No wax removal to deal with.  Plus the price is much lower than West.  If you buy the Raka epoxy in the 3 gallon kits, the prices get reasonable.  The shelf life of the Raka is over three years.  But you need to store it in the dark.  A cool dark basement is perfect.  Thats were my extra bottom paint stays as well.

Make sure you buy extra dispensing pumps.  

The pumps are worth every penny!

Plastic hot beverage cups work well for mixing small amounts.  Paper cups of a 12-14 oz size seem hard to find.

Buy some mixing sticks.  Jamestown has them.

Jamestown Distributors has all kinds of fillers so you can mix up some filler easily.

They are good to deal with.

Look at Amazon as well.  Im pretty sure I bought some filler from Jamestown, via Amazon, and it was cheaper than Jamestowns website.

If you've never done epoxy, start in small batches, like 8-10 oz.  Put it in a cup, if the cup starts getting hot, get ready to set it someplace.  If it goes exothermic, it will start setting up quickly, and it can burn your hand.   I was on a ladder the first time that happened!  Having a pail of water handy is not a bad idea.

That can occur if your hardener is too fast for the ambient temp.  

Dave

10M #26

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[James Weiner]

J

Please keep us informed of your work.  I have a P26 I am beginning to work on and I need to patch the keel also.. 

[Jonathan Boright]

Dave, thanks for the comments. Raka epoxy sounds like a good product... unfortunately, it looks like it'll take two weeks for it to get to me, so I'll probably go with West System (available off the shelf at West Marine... at the low low cost of an arm and a leg), at least for this round of repairs... I'm sure there will be more in my future though, so perhaps I'll order some Raka for the next round. 

A technical question; If I grind down through the gelcoat to the FG and then apply epoxy (unthickened, then thickened, then fairing)... I'll end up with some areas of epoxy on top of gelcoat... at least at the edges of the ground-down area. Will this be an issue? Also, do you have any suggestions for paint to cover the fairing (either good experiences or what to avoid)? 

Cheers!

Jon

PS James, I will indeed try to keep this thread updated with my progress... I'd be happy to see what you have going on with your boat too. Post away when you can! :-)

[Guy Johnson]

There won't be much epoxy on top of the gel coat because you'll be sanding everything fair to the original shape. 

When everything is faired and ready for paint, you could hot coat. Put down a layer of epoxy, let it tack up and apply a layer of bottom paint. This will encourage a chemical bond between the epoxy and the first layer of paint and should provide a good base for additional bottom paint. 

Guy

Puffin 10M #6

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[Dan Pfeiffer]

I'm sure you will get by fine with what has already been suggested.  But depending on the condition of the rudder and, specifically, the rudder post I might take it a step further.  The original rudder post on the P26 is aluminum and vulnerable to corrosion and excessive wear at the lower bushing.  See this page about wear on the rudder post:
http://dan.pfeiffer.net/p26/rudder.htm
Many P26's have replacement rudders with SS shafts.  Much better. 

If the post is sound I would strip the rudder bare, down to the fiberglass, then do all the repair and fairing.  After all the fairing is done I would coat with 5 to 7 layers of West System Epoxy.  First coat neat then 5 coats with 422 barrier coat additive, then one coat neat for easier final sanding.  Maybe two coats for a total of 8.  All this done in hot coating method where coats are added before previous coats have fully cured.  They should still be tacky or able to dent with fingernail.  This will totally seal the rudder from water intrusion.  Best would have been to do the stripping/sanding after haul out and let it sit and dry all winter then do the repairs and barrier coat.  Maybe wait a few days after stripping as it is. 

That's a more involved process but the result will last the life of the boat.  But if that post isn't good you might be wasting your effort. 

I stick to the West System because I understand it and no one knows their product better than West and they have excellent tech support.  Other systems are likely also good and some may handle easier.  But I have not used them.

Dan Pfeiffer

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[Dan Pfeiffer]

Here again is some info and guidelines I have compiled on general fiberglass repair.   If you follow them I think you should have the best repair possible on whatever you are repairing. 


FIVE GUIDING PRINCIPLE FOR FIBERGLASS REPAIR

1. PREP SURFACES PROPERLY
2. NEVER ADD NEW TABBING OVER OLD TABBING
3. MAXIMIZE THE SURFACE AREA OF SECONDARY BONDING
4. MAXIMIZE PRIMARY BONDING WITHIN THE REPAIR
5. MAKE SURE TO USE COMPATIBLE MATERIALS

More detail...
1. PREP SURFACES PROPERLY
clean and de-grease, then thoroughly sand after that so you don't just grind junk into the surface that might interfere with the bonding.  For epoxy repair sand to 80 grit.  Sand off any paint on any wood surfaces where you will be bonding with epoxy.  Bare wood and 80 grit surfaces.  Then clean it again.  Clean the surfaces with acetone or alcohol or some other appropriate solvent.  Do not rush or skimp this part.  It should probably take most of your time in the repair process.  The dust from sanding/grinding this stuff is nasty and dangerous.  Use asbestos rated respirator.  You can sand and grind at slower tool speeds to keep from kicking out as much dust.   There are sanders and grinders that collect most of the dust.  Expensive and worth it to me.  (e.g. Festool RAS115)

2. NEVER ADD NEW TABBING OVER OLD TABBING
Old tabbing will be with secondary bonding (mechanical bonds), probably with polyester resin.  Epoxy is about 170% stronger in secondary bonding but you have to remove all the old polyester bonding to get that advantage.  If you add new tabbing over old, even with epoxy, the bond strength is only as good as that original polyester.  Remove all the old tabbing - it comes off a lot easier than you expect.   You can probably peel it all off with minimal dust rather than trying to grind through it. 

3. MAXIMIZE THE SURFACE AREA OF SECONDARY BONDING
The larger the surface area of the tabbing or patch the stronger the secondary bond of the repair.  Spread it out as far as manageable and taper the layers.  The layers should taper down to one at the edges.  About an inch more per layer will work. 

4. MAXIMIZE PRIMARY BONDING WITHIN THE REPAIR
Do the repair in a continuous process with each layer being added before the previous has cured.  This is called hot coating and it provides for primary bonding (chemical cross-linking) of the layers within the repair.  The bond to the original surface will still be secondary but the bonding within the layers of the structure of the repair will be primary.  If you let a layer cure then sand and prep for another layer the bond between those layers will be secondary.  Not nearly as strong.  Avoid that.  For a structural repair you want as much primary bonding as possible.  If you have an inside corner to tab over you want to start with a fillet of thickened epoxy.  The tabbing over the fillet should be done before full cure of the fillet to have primary bonding between the fillet and the tabbing.  That also reduces the tendency for the tabbing to peel from the surface which is a common way tabbing fails.   Plan out the tabbing so it can all be applied with hot coating.  You see a lot of examples (on youtube) of people doing layers of epoxy and letting it cure between layers.  They say they let it dry, then sand and add another layer.  This is NOT the way to work with epoxy and misses one of the biggest advantages you get which is primary bonding between the layers when hot coating. 

5. MAKE SURE TO USE COMPATIBLE MATERIALS
Make sure all your materials work properly with each other.  Fabric for polyester resin has some binders on it that dissolve in the polyester resin but don't work with epoxy.  The fabric will still wet out but it's harder to work with.  Make sure whatever fabric you use is OK with epoxy resin.  Same goes for additives like thickeners for fillets.  If you stick with one brand (West System or System 3) you will be fine.   And don't skimp on materials.  In the end it is a small part of the expense of a repair even for DIY.  Better materials have superior performance and are easier to work with.   Be sure any wood you use is good for marine applications.  Use marine grade plywood, mahogany, white oak.  Do not use red oak, pressure treated pine or typical plywood from the big box store.  You can seal all the edges of the wrong woods but it will still be inferior.  Better yet don't use any wood.  You can get fiberglass panels and structural shaped pieces that are excellent for repair work like this.   I would try to use that rather than any wood.  Like with sanding/grinding the dust from cutting this stuff is nasty.  Use asbestos rated respirator. 


Do all your work with these principles in mind and you will have the strongest repair.  Sometimes you have to compromise.  You may have to glue in a part and let it set before tabbing over.  That's sometimes what has to happen but if you always work to these principles you will have the best repair.   If you have to decide to do A or B just figure out which sticks better to these principles and go with that. 


I stick with West System epoxy because I understand it.  Other brands may be just as good.  I use West System fillers and additives and West System fabrics.  For these sorts of repairs I like biaxial fabric for strength, especially the 727 4" tape which handles really well.  Sometimes I'll finish with a layer of woven fabric which leaves a smoother surface that cleans easier.  That's harder on an overhead repair.

Fiberglass from McMaster Carr in various shapes and sizes...
https://www.mcmaster.com/fiberglass/
I just used some of these fiberglass angle for motor beds and a battery box mount.  Great stuff.
https://www.mcmaster.com/fiberglass/shape~90-angle/

Also, prepare for this work to be messy.  Seal off the rest of the boat if you can to keep dust from spreading everywhere (slower tool speeds help with this).  Mask over stuff you don't want to drip resin on.   Use lots of gloves and cover your arms and head.   




Bonding Basics - Primary Vs Secondary Bonding
 
In fiberglass construction there are two types of bonding, primary and secondary. In primary bonding the resin that bonds the layers of glass together is cross linked (resin molecules intertwine) to form a continuous structure. Primary bonds can only be made if the additional layers of glass/resin are added before the previous layer has cured. Layers added after curing are attached by secondary bonds. They are simply glued to the previous layer with no cross linking of the resin molecules. The strength of the secondary bond relies on the adhesion of the resin to the underlying surface. Both polyester and epoxy resins are good in primary bonding. Epoxy is superior to polyester in secondary bonding.
 
When a boat is laid up the entire hull is made in a continuous process resulting in primary bonding throughout. When components and structures are added post cure, the bonding of these units to the hull is secondary. Components that are installed with secondary bonding include engine beds, floors (transverse stringers), stiffeners, knees and bulkheads. The hull/deck joint is also a secondary bond. When making repairs to a fiberglass structure the bonds to the old fiberglass are secondary. Epoxy is better for these repairs because of it's superior strength in secondary bonds.     
 
Tabbing is used to add strength to secondary bonded, structural members like bulkheads, floors and interior fixtures of wood or fiberglass. Epoxy with filler can be used to form a fillet where structureal members or fixtures meet (typically at right angles). Glass tape applied before the fillet cures will form a primary bond to the fillet and a strong secondary bond where it laps onto both meeting surfaces. Biaxial tape or fabric yields the highest strength in these highly stressed applications.     

References
Gerr, David (2000) Boat Strength, International Marine
Gibbs & Cox, Inc , (1960) Marine Design Manual for Fiberglass Reinforced Plastics , McGraw Hill 


Resources
https://www.westsystem.com/app/uploads/2023/09/WS-User-Manual-2020.pdf

[Jonathan Boright]

Thanks to you both for the solid info.

Dan, I'm pretty sure that my rudder post is SS... but now that I think of it I'm not sure that I'd be able to tell the difference. The surface is shiny (meaning that it doesn't have the dull matte look of oxidizing aluminum)... is there a sure-fire way to tell? Ordinarily one could tell by the weight... but with the rest of the rudder attached, weight doesn't tell me anything (except that the whole thing combined is pretty darn heavy). 

It certainly needs some cleaning and polishing, but I don't see any significant wear around the bushings. This makes some sense because the whole lower bushing was sticking to the rudder shaft and rotating in the rudder tube. There was a bit of play there (before I dropped the rudder), so I'll need to polish and grease the bushing-shaft interface (with grease), and then secure the bushing-rudder tube interface (gflex perhaps? or thickened epoxy?). 

I'm also noticing that there is a caulking seal around where the shaft goes into the rudder... it seems pretty degraded and I will re-caulk it before remounting it. A small amount of water leaked out from there when I first laid it down... so perhaps I'll remove the caulk and turn it upside down for a while to see if more will drain out. 

 

 

[Jeff Griglack]

West System epoxy is good, but so is Total Boat (and shipping is fast) and System Three.  All of them know their product well, and the last two are usually cheaper than West System.  I have been leaning toward Total Boat these days.

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| Jeff Griglack             "Jabberwocky" P-365 #269

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| "Don't take life so serious, son, it ain't nohow permanent"
|                   - Walt Kelly
| 'Years ago my mother used to say to me, she'd say, "In this
| world, Elwood, you must be" – she always called me Elwood –
| "In this world, Elwood, you must be oh so smart or oh so pleasant."
| Well, for years I was smart. I recommend pleasant. You may quote me.'
|               —James Stewart as Elwood P. Dowd
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[Peter McGowan]

I don't know, but I've been told, Hawk is basically West Systems under a lesser known branding.  It's made by the same folks (Gougeon), the pumps/resins/catalysts/silica/etc are all interchangeable so there's no learning anything new, and it's cheaper.  Personally I find Hawk cans are WAY easier to open (I usually end up resorting to my little tool I use for opening PVC cement cans to open West System cans, and then you need to get the internal seal off), I find their pumps are more reliable (I've managed to push a West System gallon pump down into the resin can in cold temperatures when it's more viscous).  Bottom line, I haven't used West Systems in a few years.    Agree on Total Boat, I really like their epoxy and fillers but most of the time I need it yesterday and Hawk is on the shelves at my local store while I have to wait for Total Boat to ship (it's Jamestown Distributors, they ship promptly but not faster than I drive)  I always have a gallon of Total Boat surface cleaner and degreaser on hand, that stuff is great too.  

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[Dan Pfeiffer]

That looks like SS to me.  Good.  You're in luck.

You can epoxy the bushings to the rudder tube with G-Flex.  Good choice for its superior adhesion.

If you need bushings I would consider getting them made extra long compared to OEM.  Those are about 1.5"?  I would go 3 to 5.  Might need to massage rudder tube to fit.

Epoxy in place with rudder mounted to assure alignment.

Dan Pfeiffer

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[Dave Cole]

Didnt know that Hawk is the same company as West.  They recognize they have a pricing issue apparently!

Regarding TotalBoat,  I have purchased some of their products via Amazon.  I just checked and Total Boat Epoxy is on Amazon.  I think they sell 5:1 and 2:1.  Mixing ratios with 5:1 is pretty critical.  2:1 is harder to mess up.

Depending where you live, you might get next day delivery.

Im in the sticks (unincorporated) so its almost always two days.

My Dad lives on the west side of Detroit and his deliveries are usually one day, even on Sundays.

But thats big city life I guess.  😄

Dave

10M #26

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[Guy Johnson]

I use West and I use the pumps, so no issues with ratios. 

I do waste some product when I only need a small amount, it's worth it to me to get the right mix. 

Guy

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[Dan Pfeiffer]

You can mix West System (or any other epoxy) by weight (a cheap kitchen scale would do) or by volume using a graduated syringe
https://www.amazon.com/s?k=graduated+syringe&crid=1YGYNN2PJSZJ8&sprefix=graduated+syringe%2Caps%2C235&ref=nb_sb_noss_1

or a graduated mixing cup. 
https://www.amazon.com/s?k=graduated+mixing+cup&crid=1XA2CBRP0JFI1&sprefix=graduated+mixing+cup%2Caps%2C116&ref=nb_sb_noss_1

It's all pretty easy.  You don't have to rely on the pumps.  You can trasnsfer the epoxy and hardener to squeeze bottles for easy dispensing.
https://www.amazon.com/s?k=squeeze+bottle&crid=X0Q2PENEOQOL&sprefix=squeeze+bottle%2Caps%2C241&ref=nb_sb_noss_1


Dan Pfeiffer

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[Dave Cole]

You'd have to use pumps to get 5:1 right, or graduated measuring cups in small quantities.

With 2:1, I can mix it without pumps and be ok.

I clogged up a pump beyond repair recently.  Couldn't find my spares of course.

Two parts of resin to one part of catalyst is easy.  A sharpie mark on a paper cup is all I needed.  Its just more critical and difficult with 5:1 in small amounts.  Thats my only point.

I don't see any advantages to a 5:1 mix?  Am I missing something?

Dave

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[Jonathan Boright]

OK... now for the second FG project: The transom.

Here's what it looks like from the outside (yes, it needs a bath first): 

 

 

 

The inside is pretty hard to access... I took these next pictures by getting under the cockpit and then reaching my iPhone (rather blindly) into the area between the motor well and the glass of the exterior transom.

 

It looks like the transom is/was cored with plywood (now very rotten), and the plywood extends down to slightly below the bottom of the motor well into the space below. There is tabbing only on the upper sides of the plywood, not on the bottom, so the unencapsulated rotten plywood is just hanging out there.  The FG on both the motor well and outside (aft) of the transom is in pretty rough shape.... it looks like there was once a motor mount bolted on, but all that remains are a few through-bolts, some screws, and a lot of collateral damage 

So... clearly the rotten plywood core needs to go, but I'm not sure about how to replace it... and with what material (plywood, Coosa, PVC board...). Here is my best guess at a strategy:

1. I'll attempt to do as much of this repair as possible from the inside of the motor well and keep the outside (aft) transom FG skin as intact as possible. So... I'll cut out a section of the FG on the inside of the transom (in the motor well), perhaps an inch from all sides. I'll try to remove all the rotten core through that hole.
2. The transom, as measured from the inside of the motor well, is only about 7" deep, 20" wide, and ~ 1 3/4" thick at the top lip.  I'd try to keep as much of the 'lip' of the transom as possible... so I have a surface to tie back into (and I can retain the correct shape and thickness). Once I remove the aluminum rim and all the failed caulking, I may discover that parts of that lip are not salvageable... We'll see. 
3. Through that opening, I'd prep (sand and clean) the interior and cut some new core material to fit into it. Ideally, I'd use Coosa, Baltex, or some such non-wood material, and the new core would be one solid piece, but the geometry and choice of materials will make that difficult. Perhaps two layers of 3/4 " (or three layers of 1/2") board bedded in thickened epoxy would suffice?  An additional complication is that the transom is slightly curved. Fitting flat core material to it will be more challenging. Perhaps cutting kerfs in the core so that it can bend a bit? 
4. Glass over the inside with layers (how many?) of epoxy, FG fabric (biaxial?), thickened epoxy, and fairing... sanding smooth in the end. 
5. Paint  

Questions (a few of many): 

• What is the best material to use? Is multiple layers a bad idea? I'm on Jamestown Distributors web page now... they have Baltek Airex PXc Boards 1/2" by 2' by 4' (they are out of stock for the 3/4" thickness). A stack of three would work to fill the space, and if I needed to install them in pieces, I could stagger the joints.  
• Would adding a layer of FG to the exterior (aft) make sense as well? 
• Because I'll be using epoxy resin, I'll need to paint (not gelcoat) the final surface... How do I handle the transition between paint and gelcoat on the side of the motor well and the exterior of the transom? 

Leaving it here for now... 

Cheers

Jon      

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Jonathan Boright

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[Guy Johnson]

You need a core material with good compressive strength, that rules out most foams and balsa. 

Probably Coosa board and plywood are your best choices. 

I would choose marine plywood, no voids and waterproof glue. Easier to find than Coosa and most likely less expensive. 

You could use a vacuum bag to drive resin into the plywood before building up your transom, I think this is a nice to have, not a necessity. 

I would add a layer of 1708 glass between the layers of plywood to help take up any irregularities. 

Also I would do this work from the outside of the transom, extending the outer layer of core material past the original core material location and make each layer a bit smaller until you get to the last layer of core material which would be the size of the original core material. 

At least 3 layers of 1708 on the inside and outside of the transom. Maybe 4 layers. 

Dan, what do you think? 

Guy

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[Jonathan Boright]

Thanks Guy! 

Good info, and more to think about. 

Doing this from the outside certainly sounds easier. So, to be clear, you are suggesting removing a chunk of the exterior (aft) side of the transom and installing a new transom core built up of several pieces of plywood (2 layers of 3/4" would do it), right? In this scenario, would I keep the interior transom (motor well) FG skin? You suggest using 3 layers of 1708 on both the inside and outside of the new transom piece... would the inside layers go on top (motor well side) of the existing FG surface or on the inside? Would I reuse the exterior piece of FG that I removed or start from scratch on the outside? 

Also, If I did the gradually smaller sizes of core material, I'd need to cut the existing tabbing between the motor well and the external layer of transom FG. Would this diminish the strength of the system or would the new built-up transom be sufficient?

Thanks again.

J

J

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Jonathan Boright

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[Guy Johnson]

Given the amount of damage to the inner skin, I'm suggesting that you replace that part with new composite. The layer could wrap over the fore and aft walls of the engine well. 

Guy

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From: pearso...@googlegroups.com <pearso...@googlegroups.com> on behalf of Jonathan Boright <jbor...@gmail.com>

Sent: Wednesday, June 19, 2024 2:25 PM

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[Dan Pfeiffer]

I generally agree though I would prefer to do re-coring from inside because the outer skin is typically a much stronger layup than the inner skin.  But access may likely preclude that option?  And I see a good bit or roving on the inner skin there in the photos so perhaps Pearson built that a bit better than typical inner skin given the outboard mount? 

For gluing two sheets of plywood together using chopped may might be better than 1708?

I would also consider adding a angle plates made from 4x4x1/4 structural fiberglass on the side faces of the outboard well and glues to the inner skin of the transom.  That would significantly stiffen the transom and better distribute the motor loads. 
This stuff:
https://www.mcmaster.com/8542K34/

Just mind that you don't create a spot that can collect water. 

While you're at it glass in a better drain for the motor well.  That stupid tube is awful.  I did it with a PVC tube.  I should have gotten a fiberglass tube. 
http://dan.pfeiffer.net/p26/drain.htm

Dan Pfeiffer

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[Peter McGowan]

Quick one - The upper end load on my mainsheet is 1800lb.  If I have a 4:1 setup with a pair of fiddles then the load on the mainsheet is 450lb.  When choosing fiddles do I use those rated to 450lb or 1800lb?  

Maybe I am not understanding things?

[Bob Maxwell]

I believe the load on each block is 1800 lbs in that scenario. The mainsheet is distributing the load internally and each roller has a portion of the load, but the total load on each block is still 1800 lbs.

Bob

On Wed, Jun 19, 2024 at 5:42 PM Peter McGowan <mcgowa...@gmail.com> wrote:

Quick one - The upper end load on my mainsheet is 1800lb.  If I have a 4:1 setup with a pair of fiddles then the load on the mainsheet is 450lb.  When choosing fiddles do I use those rated to 450lb or 1800lb?  

Maybe I am not understanding things?

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[Peter McGowan]

Thanks for clarifying Bob, that’s super helpful 

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[Jonathan Boright]

Thanks gentlemen,

I think that the conceptual problem I'm having here is that the transom core isn't bounded (constrained) by anything on the edges below deck. The core just fits into the space between the outboard well and the aft transom skin, but it is free on all sides except the top (the lip). When I'm laying this up , putting the pieces together and bedding them in thickened epoxy (no matter if I go in from the motor well side or the aft), what holds everything in place? Unless the thickened epoxy is very sticky (again, first time using it so I don't really know) what will hold it all together while it is being assembled? and won't the epoxy just drain out of the bottom while it is curing? 

Apologies if this is a dumb question... awaiting enlightenment. 🙃

Jon

 

Jonathan Boright

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[Guy Johnson]

Mix enough filler into the epoxy to give it a mayonnaise to peanut butter consistency. Colloidal Silica West 406 does a very good job of thickening epoxy. Hi density filler West 404 adds strength. They can be used together, I like to add enough 404 to get to mayonnaise and then add 406 to approach smooth peanut butter. 

The epoxy will be thick enough to stay in place. 

When you're laminating in the plywood use a couple of clamps protected by wax paper to hold everything together while the epoxy cures. 

You're right about the way the original plywood was positioned, likely after the deck was secured to the hull. Not really what I'd call core.  Your repair will be stronger than the original. 

Guy

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Sent: Thursday, June 20, 2024 5:44 PM

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[Jonathan Boright]

Thanks Guy. 

I have some 406… I’ll grab som 404 too. 

J

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