170 (1974) Rebuild - B0528

[Gmack52]

Instagram Thread on this boat: @Aquasport170

TL/DR:  Boat needs a new Transom, soft spots in the floor replaced. I haven't done anything stupid yet, what would be the best approach to this project. Thanks



Hey, Y'all!  Long time reader, first time posting.

I am the proud custodian of a 1974 Aquasport 170.  My grandfather bought the boat brand new in 1974 from "Apopka Marine Services" in Inverness, FL.  The boat spent the first two to three decades of its life fishing out of Homosassa, FL.  Unfortunately, from about 2001-2019 the boat saw little use and was left to the elements.  In 2019, I cleaned it up and got it running and enjoyed it for about a month but every time we used it we found excessive water collecting in the bilge. We ultimately sourced the water to a rotten transom resulting from a failing garboard drain and various screw holes, past and present.  Im sure you all know what comes next... The whole boat has been de-rigged and gutted.

Forgive me for not documenting anything here up to this point, but feel free to check the instagram page @aquasport170 for the majority of the process.

Now, where Im hoping y'all will come in. I am turning to y'all for help in making the decision that will guide the next steps of the process.

Transom: The transom is shot. I have decided against the 'poured' approach.  I have seen several other threads here with success at replacing the transom from both the inside and the outside.  I am not opposed to either, but I feel as if the approach from the inside yields the strongest finished product.  I plan to use Coosa as its readily available in my local area and Ive been saving up for it.

Q1: I haven't decided on the new transom shape. Im not opposed to raising it, changing it or even closing it in completely and looking at setback plates, brackets etc.  Knowing what y'all know now what approach would you take? The motor will be new/new to me, feel free to send suggestions. It came with a 75 johnson that burned up, and was replaced with a Evinrude 115. I have it, it runs, but it ain't goin back on this boat.

Floor: The floor is soft in two places. Port side just behind the front step approx 3 square feet. Port side along the edge just behind the center console approx 2 square feet.

Q2: What should I do about this. Take the whole floor up? If so, should I remove the whole floor and cap as one piece and fix it all as one. Should I leave the Cap in and cut away the floor?

Stringers: No idea.

Basically what Im looking for here is, If you had a blank hull Aquasport 170 and could do anything to it. What would you do? How would you tackle the rebuild process?

Thank you guys so much! Standby for photo dump.

[Gmack52]

Photo Dump p01.

First time in the water after sitting:

[Gmack52]

So here's the transom as it sits today. Also, Im curious to see if anyones boat has this added mounting pad for the motor. The family story goes that the boat originally had a terrible porpoising problem as delivered from the factory and had to be returned to be worked on several times. The end result was adding the pad (picture 2).

[dbiscayne]

Agree w you on replacing the transom from the inside, lots of posts on doing this. Just keep in mind you'll need to cut the strings back at least 9 inches away from the transom to get the new transom core in, then replace that section of stringer and bond to the transom & hull. Replacing for a 20" or 25" tall engine is up to you since you're replacing the engine anyway.

When I ripped my deck out the core was almost completely gone. My boat had sat under a tree, ants or mold got into the deck core and rotted the wood completely. You could always try and patch up whats soft now and use the boat a lot sooner.

The stringers on these old boats are foam filled boxed fiberglass, if the boat hasn't been kept in the water or sunk theres a pretty good chance there still dry inside.

I'd replace any thru hulls and drain hoses while you're at it.

[Fishhead]

I would have thought some trim tabs would have taken care of porpoise problem easier that adding more rake to the engine. Nice project to keep in the family.

[AquasportEd]

Welcome Gmack! Im in the midst of doing a complete overhaul on a 170 as well, if you have any questions Ill be happy to answer, though I'm fairly new to this game myself. I love the idea of an enclosed transom w/ an outboard on some sort of setback, but Im not sure that's terribly realistic with this hull. Id think raising to 25in is more realistic, but that might make it tough to find a lower HP  outboard (70-115) with a leg of that length.

[Gmack52]

Thanks for the quick replies y'all!

@fishhead - I would think so as well, they sure helped my CS J16 settle down; my guess is they weren't readily available or under warranty back in '74

@dbiscayne - I think thats what i've settled on. Correct me if Im wrong, but cutting in about 18" from the inside transom skin should give the access required. Im a little nervous as that cut would land just forward of where the rod inserts/cut outs begin in the sides - perhaps cut the floor out at 18" and take a different cut line for the sides? Thinking far ahead at replacing the floor would probably help decide, but that is another topic entirely.

@AquasportEd - I agree it would be a little more daunting to go full transom, I would have to add some knees etc to combat flexing... Im just worried bc I remember being out on it as a kid and even when it was "seaworthy-ish" for a few months and some water coming over the transom... Maybe that was because of the 15-30 gallons of unknown water in the bilge tho? Or the 12 gallons of fuel on the back deck. Im not sure, I just know theres a trend of raising the transom and exploring the motor options later. Yamaha advertises 90 and 115 25" shaft outboards on their www.

-> I found an instagram profile a while back (hope i'm not doing something wrong by adding his pictures here) that had a 170? 196? with a nice fully enclosed transom and a 115 Yamaha. Looks pretty slick with the set back and a HYD Jack Plate. I'll add a couple pics of that build below.

Again not my photos; found on instagram on the profile: @captahab239

[boatnamesue]

So here's the transom as it sits today. Also, Im curious to see if anyones boat has this added mounting pad for the motor. The family story goes that the boat originally had a terrible porpoising problem as delivered from the factory and had to be returned to be worked on several times. The end result was adding the pad (picture 2).

Dunno what the total weight is of that old motor + kicker…..add that to weight of storing fuel tanks aft….yeah, I reckon they might have battled with keeping bow down.  But I’ve got a 400lb motor hung on my ‘76 with no porpoise issue and a 13 gallon baitwell port stern, and even when it’s filled no porpoise issue.  Looking forward to seeing this rebuild end result.  Good luck!

[Fish Head]

In your first pic the hull seems to be sitting normal/ high in the water and it looks like you have a kicker hanging from the transom also. Especially compared to your yellow boat example. So maybe no soaked foam in the stringers and just a soaked transom that is leaking in your bilge. Hmm Outside transom replacement, spot fix softened floor? Just a thought. Also if you do more digging you will find out enclosing transom with not enough setback of outboard will put you in the risk of trimming motor to much and cracking hood against the transom. Yellow boat looks to have that issue. Maybe there is a way to limit the trim movement? If you are always trailering, or keeping in a slip on a lift no big deal. My boat sleeps in a slip with no lift so I really want to trim all the way up and get prop out of water. Zebra mussels are a pia in Michigan. Cheers

[Gmack52]

Alright y'all, started in on the projecting, we got a lot done this week. Ill try and break up the posts in to steps to make it easier on the forum.

Before we started in on any cutting, we followed MarcG lead and made a paper template of the floor. Also marked out the approx. placement of the console and the fuel tank coffin on the paper as well. We found the easiest way to do the paper was to build a setback block out of wood and tape a pencil to it.

[Gmack52]

Next step was to carefully remove the side pieces, again followed the approx cut lines of MarcG's thread, shoutout and thanks to Marc!

A major concern of ours was to make sure we did not make a cut line into the rod holder inserts, did not want to deal with re-glassing several layers. So, almost by accident we found that a high power flashlight in the old nav light holes (Starboard) and an old rod holder insert (Port) would yield a pretty useful x-ray of the insert/cap.  We also left approx a 2 inch Tab along the bottom, planning ahead for the eventual floor replacement.



The Dark Sharpie line is the recommended 18" cut line, we marked the shadow of the rod insert on the cap and then cut 2 inches further aft than that to preserve some tabbing.





The cutting was accomplished with minimal difficulty using a dewalt oscillating tool "vibrating saw."

[Gmack52]

After the sides came out we turned our attention to the aft 18" of floor.  Again, the vibrating saw was the tool used, although the progress through the thicker material was much slower. The floor came out without much fuss.

Found an Actual Rats nest in both outboard bilge areas. By-produdct of the boat living outside for years unattended.

We were not totally prepared for the intensity and strength of the bonding material on top of the stringers. The material was more like ceramic than anything and was very difficult to remove. More on that later.

[Gmack52]

The floor came out and we turned our attention to the transom. We found an effective method to be using a vibrating saw the remove the top gelcoat layer from the cap, and then cut down vertically approx 1/4 inch forward of the exterior skin of the transom, then come in at a 90º angle just below the fiberglass layer approx 1 inch down from the top to remove the large chunk of fiberglass at the top of the transom. Once that was out it was relatively easy to use a hammer and chisel to start removing the wood.

The Wood became increasingly poor quality the further we got down the transom, and in the bottom 3 inches of transom the wood was completely non existent. Just wet, soggy sawdust at this point. Made us feel a lot better about digging in to this restoration process.







A circular skill saw depth set conservatively and then cutting a grid pattern in the interior transom skin was very effective. Later we switched to a slotted diamond cut off wheel on an angle grinder that made very quick work of the material. The sections came off, although it was A LOT of work.

[Gmack52]

We eventually made our way down the transom to the point where we needed to address the stringers. We ended up placing the cut at 18" as recommended. The stringers came up easily but unfortunately they were indeed wet. Not sure how the moisture got in there, if anyone has any ideas, Id be receptive. Thinking maybe just over the years it seeped in? There was quite a bit of water in the bilge area at one point due to an unknown leak as I mentioned earlier in the thread.

[Gmack52]

Okay, final post. This is about where we made it to. The boat project is being conducted at my Dads Garage, due to the inhospitable nature of Florida Summers.  The majority of the transom bulk has been removed but a few areas still need work. The Stringers are out and the foam has been removed. Feeling pretty great about the progress we have made. Still a long way to go.

Probably will pick up the project again in a couple weeks.



One thing I wanted to ask the group: We found an area here in the floor (18 inches forward on the port side) that had a pretty huge fiberglass bubble filled with dry cloth. And then along the lower transom it seemed that the cloth was just crumpled up in the bottom and left to dry. Is this pretty common among other 170s?

Thanks y'all! Let us know what y'all think about the wet stringers or if you see us going wrong in any direction.