1987 170 Rebuild

[RickK]

Didnt get a ton of time to work on the boat over the weekend, but i was able to remove the last 18in of the deck/liner. Overall the boat seemed in better condition than i thought. Foam in the stringers appears dry, and from what little i can see of the transom core appeared dry. But core of the floor was saturated with water. I took a closer look at our "wavy" transom and Im now of the thought someone has patched in a repair section, as the shotty-ness appears about 4" in of both the port and strb side, time will tell.

Guess the next step in my plan is try and remove the transom core. You mentioned taking measurements then using a circular saw to cut 2in strips (im assuming horizontal). Should i do this setting a depth to hopefully not cut through the outer skin? Im also guessing I will have to remove some of the stringer to access the lower portion of the transom?

Aquasport premade the stringer shells and then laid the empty shell into the hull, glassing them in with woven roven (a heavy mat) and that is what you're seeing as being saturated. Here is an article on how the early 170s were built - https://classicaquasport.com/gallery/showphoto.php?photo=2706&title=as-170-article5-june-1970&cat=549

That being said I think I would remove the lifting eyes from the transom, you can re-use them unless they are rust stained. You also want to save the top of the transom that you see in your picture on each side. You can laminate them back to the gunwale top that you cut out already. I would also remove the bilge pump exhaust from the hull side - it'll be in the way as you build the new transom skin. Also you need to cut the stringers back 18" and gently lift them out of the boat for re-use later. Be careful when you cut them out that you don't go through the bottom of hull.
Once you have this stuff done I would use your saw and cut the transom out, from the outside and I'd leave about 2" all around the edge - that gives you enough room to secure the melamine to the aft but not have a lot of material to prep/grind for the new transom skin. It also locks in the shape of the hull bottom-to-sides. Leaving as much of the liner in as you have, also will keep the shape.

[AquasportEd]

Rickk,

Is the below cut line what your basically suggesting? Im assuming you mean to cut out the entire transom (both inner and outside skin), leaving just the 2" edge around the perimeter?

I plan on starting to cut on Saturday morning and will update as needed. Running to the store tonight to grab some fresh blades...

[RickK]

Hi Ed,
Do you have a straight edge that you can place across the aft of the transom and see if there is any outward bow in the transom? Even a string will work. Check along the hull bottom to see if it is bowed out near the drain (since that is all that will be left after cut off) also see if the corners where the transom meets the hull sides is a 90 degree joint or if there is more than 90 degrees (meaning it is going to be hard to make it flat across the transom). Check that out and let us know.
I am also concerned a little about you losing the top rear portion of the gunwale cap though. You can cut that off and re-attach it to the end of the gunwale cap on each side.

Your cut line is fine except I would cut straight up the sides out the top. The only reason you are leaving a lip is to preserve the original outer glass at the hull bottom/transom connection and hull side/transom connection. You're going to be grinding and beveling the 2" lip to a pretty sharp edge so the new glass laminations has an easy transition across the old.
Make sure to make a cardboard template of the shape of the existing transom so you can trace it on the new skin after you done the first 3 layers. Also you can use it to shape the transom core.

Here is a good example of removing a damaged transom skin and adding a new one https://www.community.boatbuildercentral.com/forum/viewtopic.php?f=10&t=11294
The reason I point out this link is for the way they used the melamine and anchored it to the back of the boat. Notice that they cut the transom out except for just a little bit. We usually use 3 layers of 1708 for the outer and inner laminations of the transom and overlap the layers 3,6,9" or 4,8,12".

[AquasportEd]

Rickk,

The hull bottom near the drain seemed flat, as did the sides. However, when I moved up towards the scuppers the wavyness of the prior repair became apparent. Looks like the centerline of the transom was the high point, but it was kind of all over the place. Looks like the past repair left about a 4-6" perimeter of original material. This was sort of confirmed when i removed the lifting eyes and saw the original wood core. 

Grabbed some cardboard yesterday to make a template, if i have some time after work today ill trace it out. Also bought some carbide blades. Looks to me that if i leave only a 2" edge i will be cutting through the original wood core and not the pourable.

[Fish Head]

Grinder with a cutoff wheel does a pretty good job making those transom cuts through the fiberglass. Don’t have to worry about the blade breaking or going dull. Just don’t forget to wear your mask!

[RickK]

That's good about those areas being flat - the center will be cut out so it doesn't matter.  You'll be removing all the remaining wood and grinding everything out to 18".
I agree about the cutoff wheels - they are cheap and make quick business of what you're cutting. Harbor freight again for the angle grinder and the cutoff wheels. Grab a face shield while you're there.

[AquasportEd]

Finished cutting out the transom this morning. I made a template on cardboard  yesterday, and also scribed my cutline, 2" in around the perimeter. I still need to remove the last 18in or so of the stringers.


Any recommendations on where online to buy the materials needed to glass the exterior transom skin, and maybe a rough idea of the quantities of materials needed? I have no real past glassing experience. 

[RickK]

Wow, great job Ed - I realize it's scary because of all the unknowns but we'll help you though this.
Where are you located? There are several places that you can buy supplies online but doing so kills you on freight. I bet I have several hundred in shipping just from East coast of FL to the West coast.
It's cheaper if you can find a local supplier - right now you don't need a ton of supplies but it does add up quickly.  At least you don't need rolls of glass - that is heavy to ship. Let us know your location and I'm sure members can steer you to a supplier.

[RickK]

1708 is what you want and if you're thinking epoxy, you're thinking right. Structurally it is many time better than poly or vinylester. Everyone has their preference - I used both epoxy and poly on my rebuild. I used epoxy below the floor and poly above. 1708 comes in 30" and 50" wide.  You'll also need some chop strand mat (CSM) and that usually comes in 1.5 and 3oz weights (still same widths).
Here is an example of layup schedule that we usually follow - https://classicaquasport.com/smf/index.php?topic=9991.msg87558#msg87558

US composites has a good explanation of the different kinds of glass - http://www.uscomposites.com/products.html

[wingnut]

If you can't find stuff locally, check Jamestown Distributors. They often have free shipping (or with a small surcharge for big items) and they will pretty much have everything you need, with reasonable prices too. They also have some pretty good video tutorials, for stuff like gelcoat nonskid techniques, etc.

Looking forward to seeing your rebuild come together. The 170 is an awesome skiff, I love mine and truly think it's the perfect small boat.

[AquasportEd]

Really appreciate all the help here. Think Im mostly concerned with getting the correct materials and doing the layup correct.

Rickk, you mentioned earlier a typical layup on the outer skin would be 3 layers of 1708. Should i be looking to purchase a 50" wide section that is about 10 yards long (enough to cover the transom 3x)? Based on browsing that other thread you linked, i should also be planning on a layer of 3/4 mat for the final outside layer? I was planning on using epoxy, so Ill need to grab that as well. Think i have some shops w/in one hour drive of me that can provide the materials (Defender Marine in CT).

Although expensive, it looks like I may be able to source a 1.5" section of coosa 26. I may be going in that direction for the core material.

[RickK]

You'll need 3 layers on the outside plus one layer of 3/4oz CSM mat plus 3 layers on the inside plus the 3/4oz csm. The CSM is more for giving you something to fair and for the resin to integrate with. If you use standard 1707 cloth it has a layer of 3/4oz csm sewn in on one side already.
Seems 1708 bi-axial cloth comes in 38" and 50" width rolls. I think a 38" roll will be adequate. How tall is your transom from 12" out in the hull bottom and up to the top?  If it is less then 38" I would go with a 38" roll. If it's more than 38, how much more? If only 1 or 2 inches you can adjust the overlap in the layers to compensate. 50" is overkill for a narrow beam boat. To measure for the length - measure across transom and then add 24", 16" or 8" (these are the overlaps). Typical over laps for best strength is 12",8" and 4" - some people go with less.
You can also buy 1708 in a 6 or 12" wide tape. You should also buy a good pair of shears to cut the cloth.

Plan on buying some chopped strand (get a small amount of 1/32" milled fiber and 1/4" strand) and cabosil (http://www.uscomposites.com/fillers.html) to make putty to use for making fillets to round out corners - 1708 doesn't like to traverse sharp corners. When you add the core to the transom, you should lay a good fillet of putty around the hull side and bottom to bed the core into - this avoids sharp corners. Also you trowel thickened resin onto the hardened transom glass and also the core and then clamp the core in. Fill any gaps around perimeter with putty - I usually use a gallon freezer bag and cut a corner off so you can squeeze the putty into where you want/need it. To mix the putty add resin, filler and then mix to get to consistency wanted (like peanut butter) - then add hardener for the amount of putty and mix. You can use rounded paint stirrers or a wooden spoon or make your own in the shape you want. The beauty of epoxy is that it doesn't harden fast, so you have plenty of working time.

Also buy a bunch of mixing buckets - I like the clear ones that have markings on them to measure content. buy one gal and smaller. You can re-use them.

Epoxy - usually has a slow, medium and fast hardener option. I would stick with medium. The slow, depending on temp/humidity can take a few days to harden and then in will run down the transom and pool at the bottom. Here is a good explanation of epoxy - http://www.uscomposites.com/faq_epoxy.html#28

[AquasportEd]

Rickk,

Guess I'm having a hard time envisioning exactly what the next step is, and how the glass will be laid. Sorry if it seems trivial, but again I've never glassed before.

First thing is I'm guessing ill need to remove the last 18in of stringers, and somehow remove what's left of the original transom core. Then grind everything back to bare glass.

I looked over this thread you posted earlier. (https://www.community.boatbuildercentral.com/forum/viewtopic.php?f=10&t=11294)

Looks like they are clamping a piece of Melamine to the transom for use as a dam to build up the glass. I'm not quite clear on what happens next.

Am I just cutting a sheet of 6oz cloth that will overlap the hull 12" on either side, as well 12" across the bottom (blue line in pic)? After that cures, laying another sheet that is 8" overlap (green)?
Wont the first layer bond to the Melamine? They state in the thread that "The melanine is coated with mold release wax and PVA", is that something they added?

After all 3 overlaps have cured, am I removing the melanine, then wrapping a final layer of 1708 across the outside, overlapping the exterior of the hull a few inches?

[RickK]

First thing is to gently cut out the 18" of stringers - set them aside for safe keeping.
Next is to remove the remaining core and grind down the inside lip all the way to the hull (sides and bottom). A 24 grit flap sanding wheel will make short business of this.
Next is to use the same wheel to grind down the hull sides and bottom to clean glass. The 2" lip around the rim of the transom needs to be ground down at a slope from the edge at a sharp edge down to the side or bottom. This will make the cloth transition onto the melamine nice.
If you want to follow Bateau2s example, which is a fine way to do it, I would get all the prep done and then set the cardboard into the hull. Then trace the shape of the old transom onto the melamine. This gives you an idea of where the cloth can be wet out to and where not to. You can wax the melamine (a few coats) or get mold release - see if the supplier sells small qty or the same with PVA.

If you follow my rebuild I took a different approach than was taken on Bateau2. I didn't cut out the transom.  https://classicaquasport.com/smf/index.php?topic=10101.msg89625#msg89625
The main thing to do is cut the melamine down to the about two or so inches above the height of the top of the transom.  Now you can clamp a 1x2 across the top of the melamine and use this to hang the 4 layers of cloth on it. If you see in my thread I ran the 38" cloth across the new transom area. Then you flip all 4 layers of glass over and out of the boat. I used 1 layer left of cloth because I still had the transom skin.
Then you flip each layer of cloth into the boat and using your shears, trim the cloth so there are not overlaps down in the corners (I think they call it "pleats") where the side cloth and bottom cloth meet. The overlap of 4,8,12 can be less it you want and you can cut the cloth so it lays down 4,8,12 or 12, 8, 4, doesn't matter because it all melts together. I took a pencil and traced the edge of each cloth overlay onto the hull bottom and sides that way I knew how far to roll out the resin. This is a good time to figure out the PVC pipe and while you're laying down the first fillets (See my rebuild), glue the pipe down. You'll need to cut pleats around it also. Typical expandable drain plugs are 1 1/4" OD. I had not though of using a pipe on my rebuild until after I saw the problem with not using one.
Oh, you'll want to use a 1/4" nap roller sleeve and you need to get a couple of these laminating roller https://www.amazon.com/BBTO-Fiberglass-Laminating-Rollers-Composite/dp/B07CV9RQ5S/ref=asc_df_B07CV9RQ5S?tag=bingshoppinga-20&linkCode=df0&hvadid=80333120120276&hvnetw=o&hvqmt=e&hvbmt=be&hvdev=c&hvlocint=&hvlocphy=&hvtargid=pla-4583932699231603&psc=1

[Tampa Bay Mike]

Good advice as always from Rick. If I could add a few cents myself it would be practice on a smaller piece first. You can do this yourself but if you don't have any experience with fiberglass I wouldn't recommend a transom as your first foray into it. There are also a lot of good videos on YouTube that will show you how to lay up a melamine mold. I like Andy with Boatworks Today and a lot of first timers seem to as well.

Do your research, plan it out and be ready for the unexpected and you'll be fine