22' Young Boat Restore Help

Hi,
First time posting, been following this forum for months very informative.
The project is a 1973 22' Young Boat 8' beam manufactured in Mass. Very solid well constructed boat.
I purchased it about 6 weeks ago and my first step has been the 120hp outboard: compression test, water pump, carb's rebuilt, thermostats etc. got it running very well except this sucker is a gas guzzler. With the 12 gal. portable tank, I ran out of gas twice. I'll have to readdress this latter on.
My next step was to strip it down and restore it to my preferences. When I removed the transducer and the motor jack plate, water started to drizzle out of the holes. Even thou it felt real solid. I decided to follow the West Systems technique in replacing the transom wood. I cut and peeled off the fiberglass skin and progressed to about 80% of the wood.
The wood was a lot solid then I thought but the water had delaminated about 70% of the glass from the wood.
Now I need some help. my intention was to remove and replace the wood and reattach the transom glass and tapper and epoxy tab it in. But after discovering the original plywood is only 2 x 1/2" laminated together with a mat between it. I feel this is not enough and my recent thought was to build up the plywood so its flush with the 3" hull and bottom strip and add another 1/2" plywood to cover all. Than laminate biaxial glass overlapping the hull and bottom. This should measure out to about 1-3/4" of plywood and about 1/4" glass ( total transom thickness 2-1/4").
The issue now, I have no experience in fiber glassing, the initial job seamed easy enough but now I've become a little apprehensive in the laminating part of the job, which epoxy , cloth ,wetting out the cloth, wrapping the cloth around the sides etc. Don't get me wrong, I have the skills and the equipment I just don't have the experience. What technique and steps would you suggest?
Sorry for the rambling , tried to keep it short.
Thanks in advance for all your help.

 

The boat is 38 years old and most likely had a lot of use. What makes you feel the original design is not good enough? Most amateur improvements do more damage than good. If you stick to the original design and take care to bed all perforations properly, you'll have a boat your grandchildren will enjoy.

 

Novo,

I am with Gonzo on this one. If the boat is almost 40 years old, and the failure is delimitation, not wood rot the transom was pretty well designed from the get go, I can't see a reason to change it now.

That being said if you are considering adding a modern 4 stroke instead of your current engine, you may want to take a quick look at the weight differences in them. At least in the smaller engines the four strokes weigh significantly more, and require different engine mounts. If this is the case in your size range, then you might want to have a designer do a quick calculation for you to confirm it's ok. I doubt it would cost more than a couple hundred bucks, and you would also get a lamination schedule from them.

Otherwise go back with what you have. As for techniques, and materials...

I would stick with West systems. They are not the cheapest, nor the best, but they aren't that much more for a product of this size, and they have everything you need from one supplier. They also have some great guides on doing this work ( there are also a lot of threads on this forum, just do a search for transom repair)

 

I disagree, a 1" transom core is too small. It should be a minimum of 1.5", which is 3 layers of 1/2" or two layers of 3/4" plywood, that is tabbed to the hull shell.

Transom core replacement is cover many times on this board, so the search tool will be helpful.

In a nut shell, don't bother trying to save what's there, assume it's all shot and rip out every ounce of previous plywood core material. Once they get rot in them, no magic goo in a can will save them, just hack out the core and make new ones to fit. Three layers of 1/2" plywood is stronger then 2 layers of 3/4", especially if you cant each layer 11 - 12 degrees to the previous layer. This orients the grain pattern to advantage and greatly improves stiffness, for the same weight.

Since you've removed the outer skin, grind the hull shell edges to a feather edge. Do the same on the removed skin. This tapered area will be where the bulk of the replacement fabrics will live. I don't like the size of the flange you have left on the hull, but it's much better then nothing. You'll probably have to wrap around the corner with your tabbing on the outside, as you just don't have much material there, but this isn't so bad and you needed to paint the boat anyway right?

You're on the right track, just make sure you error on the too much side of the laminate. Try hard to keep the transom thickness below 2.25", as some small engine clamps will struggle getting around a thicker one. Your 120 HP will be okay, but someone may buy this from you someday and try to fit a 40 HP.
Glue and screw the whole thing together, then remove the screws when it's cured. Fill the screw holes and bond the core to the exterior hull shell. Back fill the edges with a thickened fillet and then tab the whole perimeter with biax. The tabbing should be very generous and have at least 4" of hull shell overlap, preferably much more. A 1.5" core needs a lot of tabbing, at least 4 layers of 12 ounce biax around the full perimeter.

The last step, which insures you'll never have to do this again, is to bond all the through and fastener holes. Mark their locations then drill an over size hole (30% to 50% larger then the fastener shank). Wet out the hole with neat epoxy, then fill it with thickened epoxy. Let this cure, then drill the epoxy sealed hole for the fastener. If water does get past the fastener in the future, it can't get at the core because of the epoxy.

 

Gonzo thanks for the quick response.
You are right, for the age of this boat, I'm amazed how solid a shape it's in. It has no stress cracks anywhere. if I can restore the transom, it should outlast me.
So you feel, I should keeping the transom to its original dimensions and stick to my original plan: replace the plywood and reattach the transom skin tapering all the edges and tabbing with epoxy and biaxial cloth?
Another issue is the height of the transom, it is set for a 20" shaft outboard but the boat was latter fitted with a 6" Pro Hi-Jack plate and a 120hp motor with a 25" shaft. The jack plate has 4" of adjustment. The 6" adds more leverage load force?
I'm debating, if I should raise the transom.
This morning I removed 95% of the old wood and sanded to the inside glass.
The wood section measured out to be about 1-1/4" it's two sheets of ply with a glass cloth sandwich between. Maybe it was 2x5/8"?
Locally I can get Meranti BS1088 12mm, 18mm or 1"
Should I go with the 1" or 2-12mm the price comes out to be the same.
Or 12mm+18mm ( 1.18")
I would appreciate your take on what technique and steps I should undertake.
FYI:I removed the majority of the wood using a flat bar and chisel but the grinding stage I used a King Arthur Tools Lancelot 14 teeth woodcarving disc. It is aggressive and a little dangerous but in a hour I had all the remaining wood off down to glass. A little sanding with a 24 grit flap disc and it will all be done. As a woodworker I've used this disc quite often. If anybody is interested check it out katools.com

 

Novo,

As I predicted ( not really), a yacht designer chimed in and said the core is too thin. Follow Par's recommendations, and you will be fine. It's like he has a degree in this stuff or something

 

Three layers of 12 mm Meranti or two layers of 18 mm Meranti will work, with the three layers being considerably stronger. Again, cant each layer so the grain orientation is 11 to 12 degree different then the previous sheet. You also don't need mat between the layers, unless using polyester. If using polyester, I'd strongly suggest you employ epoxy. I was under the assumption that you were using epoxy and if you are, you'll be in much better shape.

From a technical stand point a 1.5" core for 120 HP is still a bit thin. 2" would be better, unless you expect a substantially smaller engine at some point later.

If you have a 25" shaft then don't cut the transom down to 20", just leave it at 25". You can always cut it down, if you fit a standard shaft outboard, but it's a lot harder to add to it, so build the new one at 25". In this regard, it's also a bit safer to have a taller outboard cutout then a shorter one, in case a breaking wave or tall following sea decides to come aboard.

Lastly, while you're there, have a look at any transom support knees that might be there. This is an area that often can use some additional support, which simply means make them taller on the transom and longer on the hull shell.

 

Thanks all for the informative responses.
Par,
I need a little clarification
The existing transom measured 1-3/4" (1/4" inside skin, 1-1/4" plywood, 1/4" outside skin)
If I add two layers of 18mm or three layers of 12mm, it will flush out to the existing outer skin flange.
Should I then attach the old outer skin by tapper grind the edges and epoxy tab with at least 4 layers of 12 ounce biax to the existing flange and around the full perimeter?
The outer skin when attached will be proud of the existing transom flange and when I grind the edge it will tapper down to the flange is that correct?
This will create a transom thickness of about 2"+
I'm pretty much committed on increasing the height of the transom to 25" and reattaching the 6" jack plate.
The existing 120hp motor weighs about 370 lbs. I suspect if the boat comes out as planed I will repower it in the near future with a Yamy 115hp 4-stroke which weighs about 412 lbs. 90hp would be the smallest motor. 380 lbs.
My plan was to use either System 3 epoxy or marinepoxy ( even thou they chastised me for trying to replace the transom from the outside)
Should I:
use a slow hardener?
Use cloth between plywood layers and skin? If so what size?
Glue the plywood to the inner, outer skin and to each other with a epoxy wood flour mix using a notch trowel?
The boat had existing corner knees for support 3" thick about 16" x 16" they were thru bolted to the transom and hull, I intend to add a corner support
I understand the technique of epoxy sealing all the bolt holes. and will definite perform on all the holes.
I know transom replacement has been covered on many post, but almost all address replacing the transom from the inside.
I've been reading and studying for the past month and only ask for help because of all the conflicting information.
Greatly appreciate all the help.
One more question:
If I decide not to use the existing outer skin what type and weight cloth would I need and how many layers?

 

An inner and outer skin of 1/4" seems a pretty stout laminate. With the outer skin removed, it'll be difficult to add to the thickness of the transom core, but it is possible. You just have to make up the thickness difference in the flanges that remain on the hull shell.

I didn't intend for you to think I was chastising you on the outer skin, but I did mention the flanges seem fairly small. This too can be handled, but again, you may have to wrap around the transom corners a bit, which is something I try to avoid when I do transoms from the outside.

The tapers on the hull shell flanges I mentioned, would bevel to the inside of the work, when viewed from behind the boat. The old outer skin would do the same thing and when placed against the core, it presets a shallow V shaped groove for the reinforcement fabrics to live.

No cloth between plywood layers is necessary, though some worry about trapped air and full contact. To address this. some will drill holes in the plywood layers to release any trapped air, but I just "spring" the plywood layers together, which eliminates any air pockets. By this I mean I slightly bend the plywood pieces as they go in and are temporary screwed in position. Air will take the easiest path and escape as the screws are driven if done progressively from the center out (assumes predrilled holes of course). Use a structural mixture of wood flour, cab-o-sil, silica, filled fibers, etc. for this. I put it on with a notched trowel.

The speed of the hardener is temperature dependent, but since it's summer, even NY has enough warmth to warrant slow or extra slow hardener. An added benefit of slow, is you have more time to align things and smear ooze out into voids, cracks and start making the fillet around the perimeter of the core.

Bond the first layer to the inner skin and use temporary screws from the inside, through the inner skin to "suck it down". Work in a circular pattern from the center out. Back fill the edges between the edge of the core and the hull shell, with more thickened epoxy. Milled fibers are better for this then wood flour, as it glues to 'glass really well and makes a strong fillet.

Next butter up the plywood and temporarily screw on the next core piece, again back filling around the perimeter so you have good bond to the hull shell on the edges. When it's time for the outer skin, you must wait until the last core piece's fillet goo is dry to the touch. This will be a few hours. You should be able to remove the temporary screws at this point with little worry. Butter the plywood with unthickened epoxy, then butter the skin with thickened epoxy and marry them together, again with a bunch of temporary screws. As before back fill the feathered seam with thickened epoxy, but don't try to fill it, just bring it up the the thickness of the thinnest portion of the skin.

Now you apply the tabbing. Wet the tape or cloth out and stagger the seams. Bulk up the tabbing with more cloth, then let this sit until it's just lost it's tack (another few hours). Now you can fill the feathered areas with more thickened epoxy. The first coat would be best if you still use a structural mixture (micro fibers and silica), but after this you can switch to a fairing compound. The fairing compound with be sanded down flush after it cures.

The plywood should be coated with neat epoxy, before it goes in the boat. I try to do all this at once. I start by wetting out the plywood, let it sit for an hour or two, then do it again and let it sit until it's just lost it's tack. Then I wet it out again and apply the thickened goo and take it to the boat.

With just a 3" flange and 120 HP on a questionable thickness transom, I'd be afraid of cracking out the tabbing on hole shots. I like to see twice this much in a flange, so you can wrap around the corners of the transom with tabbing, which will solve the problem. If you do increase the core thickness, then you pretty much have to do this. Naturally, the sides of the boat will also have to be ground down a bit so you don't have a hump where the tabbing will live. This is why we feather edge the work, so there's a place for the bonding material to lay, without making a hump when it's faired smooth.

Lastly unless you feel you need the jack plate, don't install it. It adds a bit of additional leverage over the transom, multiplying the torque the transom must endure. If the cutout is 25" and the ventilation plate is about 1" below the bottom of the boat, when you're sitting idle in the water, you're fine. The jack plate might save you a few inches in some conditions, but again unless you absolutely need it, see what you can on E Bay for it.

 

Par,
Your detail post is exactly the technical information I was looking for.
Thanks much!
The chastise reference was not aimed at you or this forum but was directed at marinepoxy forum bateau2.com who so far has not offer me any support.
I hope you can answer a few more question?
1. When I mix the glue and the filler epoxy do I still use the slow hardener.
2. If at the end, I want to add a layer of cloth to cover the whole transom and wrap around the sides and bottom. What weight and type cloth would you recommend?
3. Last question, If I decide not to use the old outer skin and laminate a new outer skin.
What type cloth and weight would you recommend and the sequence of laminating to reach the required thickness.
As stated in my earliest post. I'm a newbie, trying to establish a reference point with these question, I know once I get my feet wet, I should be alright.
Tanks again for the help.

 

The best thing you can do is more reading and video watching. Bateau.com has some good videos about the processes and techniques, but you should also log onto westsystem.com and systemthree.com and download their user's guides, to familiarize yourself with the various products and how they're used.

Using epoxy is all about procedures. If you do things in the correct order, things go well, but do them out of order and the crap hits the fan. This is where reading up on the products and techniques will help tremendously. This is what I did the first time I used epoxy, except there wasn't an internet to make finding information easy. I had to wait for books to arrive. I made all the usual mistakes, but learned from them. So will you (everyone does).

Reuse the outer skin, unless it all busted up and no longer a solid laminate. A 1/4" of fabric is a lot of resin and cloth to replace, so reuse what you can and save the money and effort replacing it.

The tabbing will be 45/45 biax (12 ounce) fabric or tape. This is the structural stuff and it'll hold the parts to the hull shell. If you wrap around the corners of the transom, you'll use both biax and some finishing cloth, which is a regular weave fabric of modest weight, so it's easy to finish out.

 

Par,
You're right, I forgot how much detailed techniques and steps The Epoxy Book by System 3 and Fiberglass Boat and Repair by West System show.
I've read the above, at least a 100 posts, watched all the videos and tutorials on bateau, YouTube, MAS, West Systems, Ship Shape JD Dist. and also purchased and read The Elements of Boat Strength.
I think whats happening now is information overload!!

 

Lol NoFo,

When I get information overload my advice is to set aside the project for a couple of days, and come back to it with a clear head. Then do the following:

Create a step by step procedure to follow. The more detailed the better.
Identify exactly what material you need to follow this, including tools and work space.

Then post it back on here and get feedback to modify the plan. Likely you missed something, and a detailed written guide will allow others to criticize constructively. Remember the more detailed the plan the more likely you are to get tips and suggestions to make it work out easier.

For example... One tip I remember from this process was someone suggesting using a flush trim bit on a router table to make the plywood panels exactly the same size. I have used this method before but it didn't cross my mind when reading someone's process since it was someone I just have always done.

 

I've changed my attack and decided to remove the inside skin and build the transom by securing a 3/4" sheet of melamine to the outside remaining flange. It will be used as a dam and should produce a smooth surface less fairing. I have seen this done on a few other posts with good results.
It also gave me access to lay in a 2-1/2" PVC chase.
The layup is as follows:
10 oz. cloth, 1808, 1708, DB1700, DB1700, 3/4", 1/2", 3/4"plywood, 1708, 1808, DB1700, DB1700
The issue I have is, I've work and prepared for the past two weeks scheduling with my sons to start the build on Saturday. I was hoping to lay the outside skin and laminate the plywood core in place.
The problem is I just received my first order for 6 gal. kit of marinepoxy and it came in wrong . I ordered slow hardener but received their medium hardener. What a bummer!
This is my first try with epoxy and very apprehensive especially laminating 1708. Where expecting 87-90 deg. temperature for the weekend.
If I didn't have bad luck. I would have no luck at all.
What do you guys think?
Also preparing the melamine surface I was planning on four coats of release wax and a coat of PVA.
Is this right?

 

Why are you employing combo fabrics (1708, etc.) with your epoxy laminate? All you need is biax, not biax knitted to mat.

Mat is a product used on elongation weak resin systems, such as polyester. Epoxy has absolutely no need for this material and in fact, just causes you to use 3 times as much epoxy and more importantly leaves you with a very resin rich laminate, which isn't good structurally.