According to the vide at
http://m.wsbtv.com/news/news/local/source-investigators-find-body-putnam-county/nfyK5/
Sheriff says elderly women died of blunt force trauma to the head. Now that they know how the wife has died they are looking at the house for a crowbar or whatever the murder weapon could be
So LE is not saying a crowbar but the reporter is.
Going on the premise that this was pre-planned and a boat was used to gain access to the home I was trying to come up with items that would be on a boat that could be used as a weapon.
Boat hook Round tube, usually aluminum or maybe stainless and long with a point and curve at the end to pick up lead lines. Can be used to push off docks or grab a line when you need to be able to reach longer than your arm would. Hand tool. To light for a blunt force trauma type weapon in my opinion.
Sail/line crank handle (for a sailboat) Item that is put over the roller pin that winds the sail line up into a coil. Its heavy, has a round open end that fits over the pin, with a handle that comes off the side so you can turn it. [Think winch but sideways] Hand tool. Are there sailboats on the lake large enough to have mast rigging that would hold sails large enough to use a crank handle to lower and raise the sails?
Stanchion bar. --These are guide lines post (think guard rail) that would be attached along the boat just inside the scupper rim on the outer edge of the hull. There are usually round, but the end is flat where it is fastened to the boat. This would have to have been broken off (with a lot of strength) or removed on purpose. Not a hand tool type of item.
Flag staff holder Usually a round tub that fits down inside a hollow bracket. It comes in two pieces; the part that you attach the flag to and the end that is screwed down. They do have newer flat sided ones but I think that type is all one piece and is more for a permanent type mounting; you can only remove the flag from the arm not the entire arm itself from the bracket. Not a hand tool type of item but the arm could be used as a weapon. Not sure if it would be heavy enough though.
o2 tank Dive bottle bracket/strap. --The metal strap that goes across the tank to keep it in place against side of boat. Width would be about the same as a crowbar. It would have to be broken off or removed. Not a hand tool type of item. Dont know if anyone would be doing any diving in the lake to have scuba gear on a boat and have that gear set up in that manner.
Engine Hatch Cover Lifter There are different types; flat bar like on one end, round handles with hook on end. It slides under the handle that lays flat to help raise the door in the deck to get to inboard engines so you dont bugger up your knuckles. Hand tool.
Then there is the engine tool box that most boats would carry. Boat and Engine size would dictate what type of tools. I know very little about engine mechanics except that we always carried a back-up prop and the specialty tool you needed to replace it.
Im sure there are other things as well. That was just off the top of my head from being around boats when I was a kid.