1970 170 Rebuild

[Deacon]

Just joined maybe a couple weeks ago. I appreciate you allowing me to join. Too many in projects in motion, but I took on another since I just couldn't pass up bringing back to life a boat that I first started to run around on when I was a kid.

So, here's the 1970 170 I picked up. (hopefully this pic posts and that I did it correctly)

150 Mariner on her transom... can't wait to hoist that off, check to see if she runs and sell her, likely aiming for a 90 zuk 4-stroke in that 350lb range, unless something more appealing comes up.

Planning to hoist that soon (need to get chain hoist or cherry picker first) before tearing into a horribly soft sole and a transom that desperately needs replacement.

Already reupholstered and used some Nautipoxy/Nautithane on the old teak from the Todd flip-seat and in process of patching some old holes on the console in prep for re-gelcoating.

Then, of course, the dirty work... seeing what's under the lid :)

Looking at some of your work on projects, I'm amazed... thank you for sharing the knowledge/wisdom. Thanks in advance for any insight you want to share on this project!

[RickK]

Welcome aboard Deacon.  The hull looks to be in great shape. Use this approach when posting pix - you upload them to your free photo gallery and then follow the instructions here to post them https://classicaquasport.com/smf/index.php?topic=12725.0
When you say "seeing what's under the lid" what are you referring to? Any pix of the inside?

[Deacon]

Thanks Rick, I'll definitely follow the photo instructions... thanks for steering me in the right direction.

The hull is in ok shape... some glass work necessary in 1 spot.

When I mentioned "seeing what's under the lid," I meant the sole and potentially the whole cap... hoping I don't have to tear the whole thing off. Currently planning to measure sole width at various points forward of stern (in case cap sides shift after sole is extracted), then cut sole leaving a 1" flange that I can reinforce and use as a guideline / support for a new airex sole (thinking 12oz glass beneath, 2x17oz above) on top.

While sole is out, planned to:
1) extract what I assume will be waterlogged foam from stringers, retab as necessary, etc, add vertical riser to each stringer to account for increased sole height.
2) mount two stern to console pvc pipes for cables, wiring etc and possibly a single one from console to bow locker
3) potentially extend stringers to tie into an integrated flotational bracket (debating this vs standard jackplate)
4) transom replacement (likely 2x 3/4" AB Fir) with full transom height (no notch)
5) transom knees for additional support
6) consider seating fuel tank beneath for greater stability, fueling safety (separating electronics from vent and fuel fill) and use of space under the console.

While I've searched a variety of projects that are documented, I didn't know if the group had concluded on the most efficient method to extract waterlogged foam from the trapezoidal stringers. Any thoughts on this or considerations on my plans above would be greatly appreciated.

Also, I'll share pics of the inside soon... probably would have been good to have had one with the old console and seat in (a before picture), but I jumped the gun and failed to capture.

Also, I finally got through looking at all of your work on your 170. Impressive work. Congratulations!

[RickK]

There are many ways to get the foam out - someone used a paint stirrer on a drill to break it up. Someone used a special shovel that fit in between the sides of the stringers. If the stringers themselves are still attached well, the usual method of exposing the foam is to cut the top off the stringer, leaving sections of the top to keep the stringer shape.
Does your boat have a liner in it? My boat was a 3 piece lamination - the hull, the stringers were set in place and then the liner was set in place using bonding putty.  My liner consisted of the casting deck, the floor, the transom cover, the inside finished gunwales with fishing rod inserts on each side and finally the gunwale tops . The front of the liner had the anchor line storage and the small cap for cleat and nav lights.  The liner floor/gunwales did not go all the way to the hullside, so measuring across the floor might give you some incorrect measurements.
Was the fuel tank inside your console?

[Deacon]

Thanks Rick,

Was thinking a section off the stringer tops may be the best option... should be fun scooping and vacuuming foam particles out.

The boat is as you described yours, but the original owner must not have opted for the rod inserts... just flat side of the liner all the way forward... I'm fine with that. Trying to draw the line before cap removal by perhaps replacing the sole behind the casting deck first... this should give me the opportunity to tie the liner into the hull below the sole (perhaps some floor supports or bulkheads)... may even have me carving the sides out of the liner (but doubt it), inserting some ribs instead of bulkheads and leaving extra space... not quite sure where the path will lead at that point, but trying to keep it as simple as reasonably possible.

After dealing with area behind the casting deck, I can address the soft floor in that part, perhaps add some 2" foam to create an insulated fish locker with a real locker top seal, etc.

But overall, trying to avoid removing the cap and focusing on sole replacement, including casting deck.

Also, yes, the fuel tank was inside the console... oddly opposing my expectation, no odor or signs of pin-holes.

Looking forward to removing the engine this weekend and carving up the sole while also deciding which skin to carve out of the transom. Since the backside of the transom sandwich has some waves and holes and such (no value in really retaining to maintain straight line integrity), I'm thinking I could be better off removing the rear laminate and replacing from the outside in.

The real question after doing that is the bracket situation- if I extend, I can perhaps do a moments calculation to see how much variance there would be in the original fuel placement under console with the engine placement 17" or so back and set the fuel tank where it would need to be to counteract (while half full or so... and obviously under sole install)... the rest being somewhat the same, could be ignored.

Thanks again for contributing your thoughts. Cool part is I finally have most materials on hand right now to proceed, so excited and ready to get moving.

[RickK]

Just aft of the casting deck on each side at sole level, you'll see a part of the liner that is between the sole and the gunwale liner, that seems to follow the hull itself (maybe about 18" long), going up slightly.  These parts of the liner are almost touching the hull, so if you're going to be cutting around the perimeter be careful you don't accidently cut through the hull in those places.
The first time I replaced the sole I cut around the perimeter with a skill saw leaving about 2" or the closest to the blade as I could.
Be advised that these 170 are very sensitive to weight being moved aft. I have approx 8" offset (jackplate plus spacers) and the boat acts totally different then it did before. I can't image a 17" offset. For one, you'd have to move the scuppers up a few inches to keep them above the waterline.

[Deacon]

Thanks Rick. I calculated the shift in CG (with some fuel capacity assumptions) being about a 3' shift forward of the fuel tank... so, you're absolutely right that a 17" shift would be too drastic, especially with a variable weight (fuel) shift that would get worse as you drain fuel. So, gone with that idea.

However, I do really want a full transom. So, I'll likely go with a hydraulic jackplate with 8" as you have. If my #s are correct, a shift forward of existing fuel capacity of about 1.5' should counter the 8" offset with a 350lb engine (targeting a 90 zuk). This would work fairly well in my opinion, especially if I were to consider increasing fuel capacity (creating an emergency capacity mainly used for ballast) and dropping it below the sole and shift forward. I'll recalc more exactly as I approach tank install / placement.

Also, huge thanks on the warning about cutting in the location you mentioned! Very much appreciate you sharing your thoughts and experience on this project. Itching to get my hands on it after work today, hopefully pulling that beast of a 150 Mariner off her back.

[RickK]

I have a Seastar Hyd steering system on the 170. I have a 6" JP and then found out from members that you can shear off the hydraulic lines when tilting the engine so I added a power pole adapter (.5") and 1.5" spacers which brought it out to just over 8".  I also had to change the hydraulic hose connections to stick straight up.  Works great now.

[Deacon]

Thanks again... I'll look into the Seastar... I know I have a learning curve to advance on that note, especially as it pertains to full transom closely rigged steering and such... I've dealt with inboards, I/Os, and straight transom mounts only thus far. Spoke with the company I expect to buy the zuke from and they claim 8" is enough to make it work coming out a bit to gain the adequate radius... makes sense especially since I can customize re-entry obviously. I need to advance learning curve to envision it all.

In the meantime, some fun I figured I'd share in prepping the workshop- materials area, glass rack, engine mount.

[Deacon]

Continuing to prep the shop... ordering marine ply, etc, building engine hoist (below)



Boat's transom was one of the worst I'd ever seen... can't say it didn't cross my mind a few times staring at her whether I'd lost my mind.





What a cool idea... instead of actually mounting the hydraulic pump for the trim tabs, just carve into the center stringer and stick it like a flower in a foam block... wonderful arrangement 

[RickK]

Yup transom looks soft. The problem with the old Ospreys there was no place in the aft to store anything. They should have run hydraulic hoses in the trough up to the pump in the console but the old consoles were packed with the fuel tank and didn't have any room in them.

[Deacon]

Transom is wet mush... everything through-bolted came out sopping wet with rot. You're right about the console... very little room with that tank in there. First transom replacement ahead and I'm rather certain I'll have a good bit of stringer work, let alone foam removal. Thanks again for being a 2nd set of eyes, Rick.

[RickK]

I planned my tank to be under sole and that is one reason I built my own stringers and notched them to fit the 27 gal belly tank I found. When I decided the placement of the tank I knew I was in too deep ..... but everything worked out ok - lots of work.

[larsli68]

Your transom looks very similar to what mine did. I drilled out the wood (big job...) and used Seacast instead of plywood. I'm very happy with the boat.
Been using it for 4 seasons now.

//Lars

[Deacon]

Lars,

Thanks for sharing... I've thought about Seacast and would use it but I'm fearful that the years have abused the outer laminate so badly (my straight-edge cringes as I lay it against the transom... just too wavy especially where the oversized 150 made its mark) that I need to do an outside-in transom replacement. I've faced that fear and about to do it.

While this isn't a budget project, I am going to go with a marine ply transom replacement (2 x 3/4") and possibly some knees for additional support.

Now that I've finally got the old Mariner off, I'm carving out the sole today to see what wonderful stringer condition I have... likely carving out stringer tops as well to get to the foam.

After foam removal, it's time to work in parallel a bit with fuel tank sizing and placement (currently aiming as far forward along casting deck, but potentially restructuring casting deck to allow integration for outboard weight and 8" jackplate) along with transom work, where my current thoughts are to:
- carve out about 1' of the cap (trying to go without lifting cap off) that I'll replace with stern storage boxes (small tackle box slots, etc) and temporarily use gap to access transom
- tack in a transom frame to avoid shifting
- carve out about 1' from stringers
- carve out transom leaving 1-2" rear laminate lip
- clamp waxed melamine board to transom
- begin exterior skin and core replacement (1 csm then multiple 17oz layers before core... obviously integrating into hullsides and hull with overlapping lengths)
- interior skin (similar to ext skin)
- stringer reattachment
- storage box completion (inner supports will act as transom knees)

Please feel free to poke holes in this plan... I'm all ears! Thanks!!