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Author Topic: 19 6 flatback conversion  (Read 443 times)

July 02, 2019, 03:36:48 PM
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Kerm

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19 6 flatback conversion
« on: July 02, 2019, 03:36:48 PM »
Well, it's finished.  The 1970 19 6 transom was replaced with a flat back conversion.  The new 115 Yamaha 4 stroke with a 16 pitch prop was hung on a one foot jack plate extension.  The boat seems to sit on it's lines according to a previous boot stripe and sits just a bit higher than the 8" draft that I found in the specs. 
 
Initial sea trials were just OK as at high speed the boat would porpoise and took too long to get on plane so I added 12"hydraulic tabs which were overkill as they needed such a small amount of adjustment.  Manual tabs would be the way to go  And yes, the motor is trimmed in all the way. 
 
Now it jumps out of the water and runs at 39 + mph at 5900 rpm.

The jack plate was mounted at full down with the cavitation plate at the bottom of the transom.  Sea trials has indicated that the boat runs best at all speeds with the motor at 3" above the bottom of the boat.  I did expect one or 1.5  but not 3.  The good part is that when we raise the jack plate on its bolts we will be able to get full tilt.   

July 03, 2019, 12:48:23 AM
Reply #1

boatnamesue

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  • Jason
Re: 19 6 flatback conversion
« Reply #1 on: July 03, 2019, 12:48:23 AM »
Nice write-up.  Sounds like you've got'er dialed in, congrats.  Just curious...what did the transom rebuild alone set you back?
---------------
Jason
1976 AS 170
1998 S115TLRW

July 03, 2019, 06:51:50 AM
Reply #2

RickK

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Re: 19 6 flatback conversion
« Reply #2 on: July 03, 2019, 06:51:50 AM »
 :PicsNeeded:
Rick
1971 "170" with 115 Johnson (It's usable but not 100% finished)

1992 230 Explorer with 250 Yamaha

July 03, 2019, 03:42:42 PM
Reply #3

Kerm

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Re: 19 6 flatback conversion
« Reply #3 on: July 03, 2019, 03:42:42 PM »
Jason,  the marina put in about 100 hours and they performed a 10 when all I asked for an 8.5.  They really went all out with nice details like a cambered deck that matches the gunnels and extended the drip rails.  The transom was done with very high quality marine plywood.  The plywood used was 2 lamination's of 3/4 inch x 13 plys - so 26 plys.  The deck return was done with one ply of the 3/4 with 2 plys of fiberglass.

I have done things in the past with Coosa but the guys at the marina had not used it before so at 70 years old I'm sure it will survive me. The next one I will do myself, probably in Coosa.

I still have to refoam between the hull and deck but will take care of that this winter when I haul it to FL from WI.  When the outer transom was out I used a plastic paint mixer on extensions that reached all the way to the front bulkhead to clean out the waterlogged foam-probably 200 lbs.  If I have time this winter it will also get a new coat of Awlgrip inside and out. 

I did all the rigging myself.  All new everything including the fuel tank.  I even replace the rod holders with King Starboad.  Nothing old except the fiberglass and a couple of cleats.

As for pictures,  I tried, I struggled but will try again.

July 04, 2019, 06:11:47 AM
Reply #4

RickK

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Re: 19 6 flatback conversion
« Reply #4 on: July 04, 2019, 06:11:47 AM »
Read and follow this thread to post pix.  Using this method you're not limited in file size, like when you attach a pix
https://classicaquasport.com/smf/index.php?topic=12725.0
Rick
1971 "170" with 115 Johnson (It's usable but not 100% finished)

1992 230 Explorer with 250 Yamaha

 

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