1970 170 Rebuild

[wingtime]

Wow that thing had a 150 on it! 

Way too much power and that stern must have set REALLY low in the water!

I have a 90HP Ocean Pro on my 170 on a manual jack plate.  Perfect match for weight and power.  At 301 lbs I would not want a single pound more weight back there though.

[RickK]

Sounds like you've done your reading homework.   If you only allow 12" of working space, when you're tying in the transom core (front side) to the sides and bottom, you will be down to maybe 2,4,6" overlays, maybe not even that.  Might want to cut back the cap, liner sides and stringers back 18" so you have some room.  You can glass them back together later. Don't forget the PVC pipe:
Here is a link to where I explain the thought of the PVC pipe
http://classicaquasport.com/smf/index.php?topic=13148.msg133124#msg133124

Here is a link to where I show what is actual problem
http://classicaquasport.com/smf/index.php?topic=13148.msg133556#msg133556

Here is a link to Hawgleg's rebuild that shows the PVC pipe installation to keep a drain at the new low point of the boat
http://classicaquasport.com/smf/index.php?topic=13148.msg134262#msg134262

[Deacon]

So, yes Wingtime, it actually had a 150 on her.
Rick- yes, I've been reading for years :)... ready for 18" carve-out... probably the better idea... may still do it. I'd only expected a 12" tie-in, but may carve out 18" to suit both the depth of tackle drawers and extra support... only reason I'm thinking 12" is the fact that I'll have twin knees tied in as well. Just off the cuff, I was expecting a 1" overlay of CSM (non-structural), 3" overlay of 17oz, 6" 17oz, 9" 17oz, CORE, then additional 3 that should bring me back to around 11" with core embedded. If you all don't mind, let me know your thoughts if you don't think that's enough.

Turns out stringers were crud... crushing under my own weight... sad they're that bad. I'll likely tear out and redo but I'm considering running lateral structural supports to "splint" them and move forward. Debating on replacing with vertical 1" stringers verse restoring trapazoidals.

Some fun pics from today:

Amazing what you'll find!- "Pride of the Carolinas" Pepsi soda, and a child's lifejacket!??


Coming along... takes longer than anticipated:


Stringers horribly delaminated:


Thanks again for your valuable input! Much appreciated!

[larsli68]

I totally agree with you. If it's that abused, I would have done the same thing. Mine had a small crack at the top, which I removed to get to the wood anyway. Removing the wood is something I wouldn't want to do one more time anyway...
It was a tough job...
Great progress!

//Lars

[RickK]

3" overlap (3,6,9) is fine. Working in the 12" area is the tough part.

[Deacon]

Some updates from a lunch session today :). Decided on a few things:

Stern tackle / storage stations: carving out 16" between transom and sides... enough room (thanks Rickk for the feedback on that) to overlay glass for transom replacement and fits what I wanted for storage in the form of box length. Planning to tack some 2x4's across the boat to hold form before I make the stern cut & casting deck cut.

Jackplate and full transom concept- abandoned... while I felt I could manage around it, the hydraulic jackplate rise and full transom height won't allow it (yes, some of you probably already knew that... thank you for your patience as I reached this decision) unless you shift to a Porta-bracket, at which point you're dealing with a 17" minimum offset. While my calculations indicate that may be feasible if you max out forward shift of the fuel tank and increase fuel capacity to nearly double (or add some fresh water ballast), I felt I was about to engineer in a problem for little to no benefit, so planning on 25" transom enclosed by full transom height storage boxes on the side... small seating option & bilge access hatch in the middle.

Fuel Tank Placement- researching the multitude of tank options, I finally just headed over to the shop today and measured whether the existing tank (24x14x18") would effectively fit in the space that will formerly be casting deck storage... yes, it will, kind of... casting deck wall will have to be shifted back a few inches but it's trashed anyway... I'll put in a bulkhead, extend casting deck aft, add a hatch forward of the tank and regain storage. If my calculations are correct, the shift from original setup with a 270lb engine and standard fuel configuration to a 350lb 4-stroke and 26gal of fuel in that position will leave me with COG 3/4' forward of the original setup... so hopefully she'll be in a position, with the slightly raised sole, to self-drain without water coming flowing back through scuppers... of course, low fuel will shift this but I'm no longer worried about additional engine weight.

Stringers- completely trashed aside from a large portion of the center. I think this 170 may have been used to jump tanker waves at some point... complete carnage. Fortunately, I got a call from the marine ply guys this am and was able to add to the order before it went out. I'll see if I can salvage the center stringer up to the new casting deck bulkhead and I'll likely do 3/4" AB fir outer stringers, adding some floor supports as well.

Finally, no kids sports games this weekend... possibly a full-fledged "get-er-done" weekend.

Thanks again for your feedback!

[Deacon]

All this work and she's totally not rotten  ....



Slightly wet :)


Alright... she's rotten all the way through... and even too the gunwale. Unfortunately, I couldn't carve out the rest... my Fein multimaster burned out after a month... seems odd since I wasn't pushing any limits. I'll clearly be checking on their warranty and general customer care... I'll keep you posted if you're interested... sure has been a fine tool during the very short time I've worked with it... until now.

On a different note, Poly Iso mold time. Aiming to create a hatch forward of the original casting deck hatch... planning to epoxy, then apply multiple coats of pva, non-wax gelcoat, a couple layers of csm/polyester resin to satisfy curves and such, layer of 1200, csm, 2x1200, csm, gelcoat... hope that's not overkill... have to monitor gap to surface distance on gasket ridge.

Thinking about a piano hinge from the diagonal side since forward width will be 12" and rear 30"... too much for a 12" hinge.



Thanks again for your insights and feedback!

[Deacon]

Transom is finally out. Hammer and flathead used to chip out the old wood around the edge. Hoping the sun will soak up the rest of the moisture and leave it easier to sand without gumming up. Thinking a dremel and the normal sanding barrel may be useful in the corners.



Also, finally finished routing the foam for the forward hatch, epoxy, PVA and no-wax gelcoat (glass to be layed in tomorrow)... This being the first hatch I've made, I already see some mistakes that make me cringe. At first, I thought leaving what I presume to be aluminum film would keep a smoother edge, but it tore away inconsistently... this being foam I received for nearly nothing, I took what I could get to experiment and thus the alum film version. However, I'm proceeding to see what I get, thinking I'll be able to sand the gelcoat and work around some inconsistencies. Also, learned quickly not to over-apply PVA... thinking this hatch may look like the swamp thing when it comes out, but hoping otherwise.

Currently, looking at gasket types to lay on top of the ridge and envisioning a 1/2-3/4" wide neoprene strip (smooth surface face down to ridge) with small ridges in the topside surface, offering a more variable compression across the width that contacts the hatch... perhaps I'm being picky and I supposed I can do that myself, but thinking that would be beneficial.

Thanks in advance for any thoughts or feedback.

[RickK]

Great progress. There is no value in saving the upper portion of the transom on each side.  So you have the inner portion of the transom to remove from the hull bottom/sides and to cut the top rear off at the 2" guide that you have cut all around.  Then its grind city to scruff everything up in prep of new glass.

[Deacon]

A bit of time unfortunately... had to coach some girls lacrosse and get some other work done.

With the ply in, patterned with some hot glue



cut some pieces



and wondering everyone's thoughts on whether I go through the following process or another:

- Lam Polyester- overlapping 1st CSM, then 3x 17oz
- Epoxy for inner bridging the boards together- wetting out each, lightly clamping together
- Lam Polyester- overlapping 1st CSM, then 2x 17oz, last CSM... gel, fair, gel

Other thoughts...
- planning on using waxed Melamine (probably buffed turtle wax) as a dam on the stern
- planning to fill hard edges with polyester filler (aerosil, milled fiber, resin)
- peanut butter with trowel for skin to ply bridge... bolted with vegi iol sprayed through bolts to tighten.
- clean edges, hopefully seeping with peanut butter to be displaced to gaps or removed for next laminate ease

Would love to hear thoughts to shift direction or to confirm. Thanks!

[RickK]

You can certainly do exactly what you have planned out with poly. What I would do is not get so caught up in the total plan and take it one step at a time so you don't get overwhelmed. 1st get the melamine clamped to the transom and get the outer transom skin in (this is a big milestone) and prepped for the next step which is fillets and then fit the wood core (what you just cut probably won't fit like you have it because of the fillets added and the thickness of the glass and resin).
So get the transom skin in and then go to the next step.

[Deacon]

Thanks Rick...  good to know the poly method will do the trick and your other thoughts certainly help as well... I was rather worried about whether the bond will be sufficient especially when I see so many using Vinylester or Epoxy on transoms.

No issue with being overwhelmed, however... I'm enjoying this. We get so much rain here in the Atlanta area that I'm forced to plan ahead. Outside of other rain-related issues of course, I seriously have to be selective about when I tack up the melamine to ensure it's not swollen by rain before I move forward. I'd heard we just recently had our first week without rain since Sept of '18.

Thanks again for the feedback!

[RickK]

Here is an example of a pro using poly
https://classicaquasport.com/smf/index.php?topic=9991.0

[Deacon]

Rick, that is very helpful! Read the whole thread... much appreciated!

[thill]

Poly will work well, especially on the fresh wood.  Just make sure to roughen all existing glass with heavy grits, wet out carefully, and roll out all trapped air.

Any recent progress?