Day Two:

WARNING !!!!! Unless your shaft is very new, like this one was at just a few months old, be VERY, VERY careful using this method. I hate to even suggest it but there are shaft couplings that can be removed this way if you are very careful. It is VERY, VERY easy to bend an output shaft, making future alignments near impossible, or actually break one see photo after this one. A better method is to have a plate made at a machine shop with the same bolt pattern as your coupling and use it to press the coupling off not the transmission flange.

Process:

1) Insert a deep drive socket that is slightly smaller than the shaft size between the center of the shaft and center of the transmission hub. See the picture below for a close up of the socket between the coupling and the transmission hub.
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2) Insert four long threaded bolts, preferably without shoulders (the part on longer bolts with no threads). This boat was only few months old and the coupling was not that tough to get off compared to other boats where I fine thread bolts and a custom "pressing plate". Be sure to use washers between the coupling and trans hub and begin tightening evenly. You can put never seize or Tef-Gel on the bolt threads to make them turn easier.
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3) After some initial tightening, and with the bolt pressure still on the shaft and coupling, you may need to go outside the boat and tap the prop shaft towards the bow, yes the bow, with a wood or lead mallet. Remember this is NOT a driving blow more of a "tap". This is not a pounding with the mallet, just a light strike. If you hit it hard you can brinell/dimple the bearings and or races in the gear box and ruin them.

Use a scrap piece of maple between the mallet and the shaft to prevent potential damage to the end of the shaft from the hammer if you don't have a soft metal or wood mallet. Then re-enter the boat and continue tightening until the coupling is off the shaft. You can also apply heat to the coupling while it is under pressure to help expand it and hopefully aid in getting it off. Please DO NOT overtighten the bolts. If it does not want to come off please DO NOT damage your gear box trying.
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4) Optional: Bring the coupling home to clean and paint it with a rust proof paint.


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WARNING. WARNING, WARNING!!! Be very careful NOT to get PB Blaster near ANY engine or transmission seals. True penetrating oils will EAT engine seals causing catastrophic failure of that seal. The most common seal DIYers destroy is the transmission output shaft seal. Be very, very careful using PB Blaster on your engines coupling bolts and DO NOT use the spray feature when working that close to seals. If you need to use a penetrating oil on coupling bolts fill the PB Blaster cap with the penetrating oil and then use a Q-Tip to dab PB Blaster on the bolts being very careful not to drip ANY on or near the transmission output shaft seal.