Hi Chris,

The dimensions are 13"X13"X16" ( if you include the drain then it is 19" instead of 16")

I removed it from the galley side. I removed the engine cover so that I can have more space then removed drawers under the sink, including the frame. Also must disconnect the retaining screws of the charger and move the side drawers out about 3 inches.

The original water heater was Seaward, 6 Gallon, but the new one is Whale 6 Gallon. I was told that Whale bought out Seaward.
There are more photos in the album regarding the complete installation, The link to the album is at the bottom of the content and I am posting it here for you as well.
http://mei1970.org/saillavie/c36Album/index.php?album=Water-Heater-Replacement 
Since you had posted the comment as anonymous, I searched for you on C36 international.
haro@mei1970.0rg

Yes I do check C36 international often, I am a webmaster there. You will find many postings from me on that site. I created this site since the C36 site does not allow files larger than 2Meg to be uploaded and most image files are more like 5 Meg. Other manual are also over 2 Meg that can not be uploaded. You will find many manuals here on this site as the limit is 64 Meg. Register an account on this site so that you can post content and upload images. There is an album that you can upload images and videos to share with others. On C36 site you can not upload videos.
Haro