Portable FF - 535

I am new to the site and do quite a bit of fishing and diving north of Bodega Bay.  I have a GPS that I have used in the past to mark reefs, but wanted to be a little more efficient  .  I want to purchase a portable FF  to assist in finding reefs and structure.  A few people had recommended the Humminbird 535 (Portable).  Wanted to get some others feedback before making the purchase.

jd71 - I have the 535 - but not the portable one. I've had mine for 4 years now and it never gave me any problems. I looked at the Humminbird site for the Portable Unit =
http://www.humminbird.com/products.asp?ID=478

It looks pretty bulky to me.

Thank you for the response.  It is a bit larger than some of the others that I have looked at, but space is not really an issue.  The main use for the FF is for the ocean and I have been told that if you do not have enough power the readings can be off due to the saltwater.  Please let me know if my information is incorrect.

I use two lantern batteries just like that FF does, I didn't pay for a waterproof box to protect $5 worth of disposable batteries though.  Generally they're dead by the time they are rusted out.