There is a 1-1/4' hose inside the bilge that goes from the notch in the transom directly overboard. Purpose?

Lets air under notch, helps break the vacum to get on plane easier.

yes as said above it is supposed to introduce air under the notch and break the vacum

dam was wondering the same thing

Agreed, that is the intended purpose of the hose. I ran my 35 with the hose closed off this past season, a number of back to back runs, and honestly saw little if any difference in the on plane ability. On many #6 drive setups they do a similar deal to vent the large props to help them break loose and spin up to help get on plane. My boat was breaking loose coming on plane and I wondered if closing this off might help, like said it was little help if any at all.

Only to plane the boat over, not while under way? My boat planes off effortlessly with only 2000 rpm's with the tabs down and I don't even have the drive tubes.

it also pulls hot air out of engine compartment those giving engine a little cooler air.

later

You may be thinking of something else. This hose goes from the notch directly overboard and does not introduce additional air into the bilge.

MINE COME FROM THE NOTCH STRAIGHT UP THE TRANSOM ON THE INSIDE WITH A LOOP IN EACH ONE OPEN TO THE BILGE

LATER

I don't think that Fountain did this during your model year, my '99 35 did not have them. Possibly a previous owner installed them. I would suggest that you pick up a couple thru hull fittings and rout them out the hull sides just for the safety issue. Were they to come loose and drop below the water line they would allow a lot of water to come real quick. My current boat only has one of these hoses, it is routed to the port side of the hull near the bilge pump fitting, it also has a ball valve where it comes thru the hull to allow it to be closed off there as well.