what is first year gulfstream23 & sailfish25 had seav2 h

1. What year did Grady White start building the SV2 Hull?

The SeaV2 hull design was implemented on Grady-White boats in the following sizes and years:
28 ft............1989
26 ft............1991
22-25 ft.......1992
208-209......1993
192.............1994
180.............1998

Faq's page - http://www.greatgrady.com/forum/viewtopic.php?t=7290

You can convert a portapotti to a pump out portapotti, also, to a fancier porcelein head that requires a holding tank, if there is room for the tank as there is in a Sailfish, not sure on the Gulfstream. Heads have nothing to do with fresh water shower, unless you are talking a vacuflush head which requires a source of FW to flush tank. Conventional heads use saltwater via thruhull.

The Gulfstream is a Sailfish shorter by a few feet and noticably less on cabin accomodations. I'd say there are more Sailfish on the water, meaning there are more for sale relative to Gulfs.

The Gulfstream can be powered with a single motor in addition to twins, not so with heavier Salfish.

There is no Grady model to stay away from.

Regarding heads. You may also want to consider one of the models made by Thetford. I put one of these on my Pacemaker and it works great.

That boat was (is) older and did not have a holding tank. There was no place to put a tank that didn't require a long hose run, etc. They had a model that was essentially an electric port-a- potti with built in holding tank. pump out options are then identical to a conventional holding tank.

Stay away from any you can't afford or is a basket case (with the curent martet there is no need to buy a boat that needs a ton of work). Most Sailfish will have the stand up head with a pump out. I'm not sure how much room there is in the Gulf but there is an option for the pump out head. Take a look at a few and see what you like/want.

As for power, in theory you might be able to out a 375 HP single on a Sailfish (if they had one) but you loose a lot of manuverability. Twin 200's for >1990 or at least 150's for < 1990. Gulfstreams come with single or twins, most seem to prefer twins. Given the surface area, docking the Gulfstream in tight quarters with decent wind/current can be a PIA with a single (the wind like to take my Sailfish sometimes).