1976 Aquasport 170

[MJB]

Got her home last weekend and couldn't wait to clean her up a bit and at least make it presentable.

Before cleanup

After cleanup


Sunday I pulled the motor


Here's a look at the fuel tank which is full off water and has three holes from corrosion where the water bubbles up.

One of my concerns is water that has made it's way under the sole.  I know the storage compartments forward don't drain, so here's a problem.  Looks like the access cover has been off for awhile and likely drained right under the sole.


Transom has a crack running across the top aft nearly the entire length and many many holes.  Not sure what all the holes were for but obviously added water to the transom.  Also, noticed when I pulled the motor the 20" shaft length that the motor did not actually sit on the transom, it had a gap of about an inch.  Reason being the two bottom bolts were at the lowest point of the cockpit deck, another inch down and the bolts would not have been accessible.  Is this a problem on these 170s??  Here's a couple pics of the transom.



My plan right now is to drain the fuel tank and pull that out, hopefully this weekend and see what the coffin looks like.

Now that I've had a chance to really inspect, first will be a transom replacement.  I'll have to cut the sole back and I think that will give me an indication of what the stringers look like, if the floor is wet, and how much water might be in the foam.  The only soft spot on the deck is area just aft of the fuel tank coffin.  I know the fuel tank deck core will need to be redone, the plywood core is wet towards the aft.  If I find any delamination of the stringers and/or wet foam I'll cut the deck out and replace.
It's too hot to really start all this right now here in NC -- I replaced the transom in my Mako last summer and swore I'd never do that again....since this is my winter project no hurry yet.  I'll probably hold off till Sept and start then with the transom cutout.
I've got to put a plan together and see how I want to proceed.  Couple questions -- has anyone gone from a 20" transom to a 25" transom on a 170??  Have you seen the problem I mentioned above with the motor bracket not actually sitting on the transom because of the bottom bolt location??

[RickK]

She sure looks different cleaned up Mike
The cracking you're seeing along the top of the transom is the liner cap and how they joined it to the transom - a common thing on these older boats.
As for the holes along the transom top - I bet that someone built a transom "fill-in" to close it in a bit - the 110 is a little heavy for that size boat (I had the same motor prior to the one I have now) and makes the freeboard get pretty low in the back.

[MJB]

Wanted to see how low the 170 sat in the water with that 110 Johnson -- motor weighs ~310lbs, put that fuel tank back in and filled it with water and put her in the water -- sat right along the scum line that it had.  Unfortunately the scum line is above the 3 scupper drains, thats why it had pulgs in each of the 3 drains when I bought her.



I've been thinking about putting a 90/115hp 4s which weighs about 426lbs, so needless to say it will certainly sit lower.  I used the buckets to add extra weight at the transom, I figuerd I had about 406 lbs at the transom in the second picture.



I find it hard to believe the old literature with an 85hp that it only draws 7 1/2" -- underway maybe but not just sitting in the water.  Unless I have some serious wet heavy foam under the sole, which could add to the problem.

I'm considering raising the transom to 25", here's a pic with the cardboard template.  If I go with a 90/115hp 4s I'll definately need it.  If so, I'll eliminate the tray for rigging and bring the deck flush with the transom and then add scuppers at the deck line.  I'll run a rigging tube under the sole back aft and bring the rigging from the top half aft side.  I like the idea of the tray but I'm not a big fan of the rigging laying in the tray which will likely be wet most of the time.  Still need to look at how low it might sit and how that might affect draining.  Might still be too low in the water to drain.........these didn't include any other gear or person(s) in the boat.




I'm anxious to start on the project, probably cut out the transom next weekend -- but I hate making that first cut!!

I know there are quite a few with 170s -- can you 170 owners give me an idea of the engine hp/weight you are running and where your original drains are, below or above the waterline and how much.  I'd like to get some info, maybe I'm to far out of the box thinking I can put a motor that weighs 426lbs on the transom.  I may have to consider less HP/weight.  Any info for consideration would really help.

[RickK]

I have a Johnson 115 on the back of mine and the scuppers are under water - in fact I've owned her for 19 years now and the scuppers have been under water with the 3 different motors I've had on her.  BTW - I've had the sole out, and replaced the foam already too.
I did a lot of research before I bought the latest motor, thinking I wanted a 4 stroke too and without doing what you're about to do, or enclosing the transom, I don't think the boat can handle another 100 lbs. When you come off plane there isn't a whole lot of freeboard in the back.  Now add a 200-250+ buddy in the back and it'll be worse (I saw that same issue yesterday ) 325 lbs is about the max motor weight with a stock transom on an old 170, IMHO.

[MJB]

Rick,

Thanks for the information; after thinking about this and doing some more looking I highly doubt I can put a 420lb 4s on the back and expect good things.  I checked -- boat test info from 1970 with the 85hp motor -- motor weight was about 260lbs, bit of a difference between 260 and 310 (110hp Johnson), so I guess I would expect it to sit lower.  Putting a 4s with the added weight/same hp just does not look doable at all.

Comparing to a 2s 90hp Yamaha -- looks about to be in the 260-270lb range which is more comparable.  I need to check an E-TEC and see how much those weigh in that hp range.

Biggest thing is I hate to replace the transom, buy a new motor, and not be happy with the overall boat performance.

[JimCt]

My '71 170 was placarded for 85hp max.  I ran a Merc 75 on it plus a 6hp kicker and the scuppers were considerably below the waterline at rest.  Foam in the boat was dry.  Having a dry deck in 170's is possible with a light enough engine but the performance trade-off is not worth it for most people.  The 75 pushed me along at ~32 mph with two people aboard and 25 gallons of fuel.

Looking at your pictures I'd say the probability is reasonably high you have some wet foam under the deck... especially if you have any soft spots in the deck.  Dig out the foam, replace the transom and you will float higher but not above the scuppers with any reasonably sized motor.