93 Wellcraft 196 SC - Bare hull rebuild

Woodonglass

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Dec 29, 2009
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Check the link in my signature on Fabrcating Decks, Stringers and Transoms... I think you'll find it helpful. Very Nice prep job on the hull interior!!!:clap2::sad::thumb:
 

ondarvr

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Apr 6, 2005
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Here's the deal on thinning resin.

Up front it sounds like a really good idea to reduce the viscosity so it will penetrate quicker and further into the wood, but the chemistry doesn't help you get there. Unlike a paint where the solvents evaporate out of the mix and leave the solids, most everything in the resin stays in the mix and is supposed to cross link and become a solid. As you add solvents they tend to contaminate the mix, acetone is an inhibitor that prevents it from cross linking, and styrene is only useful up to a certain %, past that is degrades the resin. When polyester resin is first cooked it's almost a solid at room temperature, so they mix in styrene to reduce the viscosity, styrene also cross links with the other raw materials in the mix and actually helps the cure take place, they add the right amount of styrene at that time to achieve the best physical properties, and this includes water resistance.

This blend now has a very low viscosity, too low for use as a laminating resin, so they add silica to thicken it so it won't drain out of the glass while it cures. Now when someone adds more styrene to thin it back down you're battling the silica and trying to reverse its function. This added styrene cross links with itself and isn't nearly as strong or water resistant as the resin was to start with. Acetone inhibits the cure and slows the process down, but doesn't cross link, so it needs to evaporate out, which it can have a tough time doing, so much of it gets trapped in the resin. It typically finds its way out over time, but now you have weak and under cured resin that has poor water resistance.

In a boat shop where speed of construction is important, they frequently don't pre wet the wood, they just lay glass on it, the wood may suck resin out of the glass and leave both laminate and wood starved for resin, this is where the poor bond comes from. Pre wetting the wood and letting it at least start to get hard before applying glass gives a much better and longer lasting product. Now if you really want to have better penetration you can buy a low viscosity infusion (method using fiberglass) resin, it won't have any silica added to thicken it up, so you won't need to add any solvents.
 

gsxrdan

Petty Officer 1st Class
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Aug 28, 2016
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All the bits ready to glass in...

Then today i found a new job to do

the cap and hull have separated along a 1 meter section, found it by accident when changing a tire on the trailer

guess ill have to pull off the gunwale rubber - can i leave the alloy trim on and pb the joint then rivet thru the lot?
 

mickyryan

Rear Admiral
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Apr 18, 2016
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did it separate because stringers were removed? id get a pusher bar and jack it out from inside to meet hull top before glassing anything in , also take lots of measurements to be sure boat is level flat and not cocked or curved in anyway
 

gsxrdan

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Aug 28, 2016
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I dont know if someone was in there before, but a few rivets are missing - everything is still tight and snug tho, i flexed the hull inwards to show in the photo.

im a bit paranoid about hull shape tho - because the boat came on a 'replacement' trailer, the hull wasn't supported correctly Ive replaced the skids, put down some keel rollers, and added a few supporting wobble rollers, and now messing with the winch post to try and make everything fit, just hoping its all supported in the right shape now...

Damn these local fiberglass suppliers, no-one sells unwaxed poly resin!!
 

mickyryan

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Apr 18, 2016
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Do this,
pull off trailer put a jack on a chine on one side in rear and jack on chine on other side make them level use a lazer if you got one or a water level,

then take and after you got back two correct go and put one on bow in front and check keel to be sure its strait and true from fro t to back. Now build permanent box to support boat like a cradle then do your work you can see how i did mine in earlier posts of my rebuild its extremely important there is no twist,
use chines as measuring point as cap wont work since it is never a perfect cut around top of hull
 

gsxrdan

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Aug 28, 2016
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Thanks mick, tho thats unfortunately not an option, it did lead me to a solution...

After using some bolts to replace the missing section of rivets (will do a permanent fix for that once the decks in and rigid) the flex in the hull almost disappeared, so i set about fabbing a cradle on the trailer frame. Will take some pics tomoz when im finished bracing it, but im happy as with the results. With new bunks/skids, and a properly fitting winch post, wobble rollers at the bow end, keel rollers, and now a 'cradle' bracing the chines, she feels solid as a rock! Far cry from the way the poor girl arrived - wobbling around like jelly on a stick. Will also have to check that all the woodwork is still in alignment...
 

gsxrdan

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Aug 28, 2016
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in the meantime, heres a handfull of rivets that i pulled out with pliers


And heres an example of the outstanding workmanship from the factory - pretty sure i can match their quality ;)
this is a 'floor' section (a rib), far as i can work out the roving is meant to be actually touching the ply...
 

kcassells

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Oct 16, 2012
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You're on a good road with great people to help you out DownUnder! Lots of pics and lots of questions....
Welcome to IBoats. Nice project.
KC
 

gsxrdan

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Aug 28, 2016
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Thanks!

Heres a question still unanswered - is it redundant putting a limpet hole in a foam filled cavity? if water gets in will it even work its way down; and would a hole just allow water to wick in?


and an obligatory dust monkey shot! safety first

 
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mickyryan

Rear Admiral
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Apr 18, 2016
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wow those look as bad as mine did rofl! must been same guy doing the layups :) my cap was even worse , yet boat lasted 28 yrs like that lol
 

mickyryan

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Apr 18, 2016
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the hole allows for air movement as well so you don't build up condensation, water will find a way in just giving it a way to air out and dry has to help:)
 

gsxrdan

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trailer framing





And some more quality controlled factory work - heres the fiberglass skin, they've cut a notch out of the bottom of a bulkhead for drainage and filled it with resin for waterproofing, then drilled the hole thru the timber next to it!!
 

gsxrdan

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Aug 28, 2016
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317
love it or wonder how the hell they are still making boats?? Hope they got a new foreman... On a positive note, my wife loves that i can pick the flaws, she has faith in my learning capabilities!! (well founded or not)
 

gsxrdan

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Aug 28, 2016
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Speaking of learning something - limber holes not limpet holes!

Have a buddy tracking down some f glass and unwaxed resin at a good price, waiting on that call, in the meantime the wife is home for a few days and wanting to help, so we're making a start on the seat bases...



and heres a shot of some cavities and the engine mounts... should i have LIMBER holes into and out of the engine mounts??
 

mickyryan

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Apr 18, 2016
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mounts are solid correct? no need if solid just anyplace that can trap air then get condensation over the years
 

gsxrdan

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Aug 28, 2016
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No the mounts are hollow, and kinda jigsawed together using 7 pieces of ply - took ages to work out how they'd built, them with not much more than imprints in the glass to follow!!

HERES ANOTHER QUESTION (in capitals so it really stands out) :

Why use wood glue to bond the transom laminates (and the engine mounts), when they've been coated with resin for waterprofing - doesn't that make a plastic to plastic joint? Would it be better then to use (eg titebond 3) on bare wood, and then waterproof it? And is laminating instead with poly resin and a layer of CSM an inferior joint? I ask because ive seen a few builds using the mat in between...?

And good news, i pick up the glass supplies tomorrow!! party on Wayne :)
 
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