You will need a substantial down payment to get a bank interested. A home equity loan is more likely.
Some people don't want to tie up their home equity up in a boat, they also don't want to deplete their savings for a boat. To these people I ask.."How do you think the banks feel?"
To buy a $70,000 boat, you pretty much need at least half of that amount in ready cash. Some for the down payment, some for immediate expenses like survey, some transportation, a tank of fuel, taxes license, etc. And some for first year improvements, electronics, a berth, storage, new canvas, etc. and then some for long term expenses like new engine, new paint color, more electronics, etc.
If you can't lay your hands on $35,000 I think you should consider a less expensive boat.
pete