Since it could be a while before I am able to sea trial this boat (it's supposed to snow today

) would you give the seller some earnest money? He hasn't asked for any but I also want him to understand that my intentions are to buy this boat as long as there isn't something hideous going on that I don't know about. I know that this is an elementary question but, as I wrote, this is my first rodeo.
a deposit and earnest money are two different things and the wording will hold up in court, no matter the intent or mistake in how it was written.
a substantial deposit to show you have a serious interest in buying
if all systems check out, may be a reasonable gesture or requirement.
a deposit gets returned if the boat does not meet your requirements, whereas with earnest money, the entire amount is forfeited to the seller if you should decline to purchase.
even with a deposit, in the event you decline to purchase, a very small pre determined amount of it may be kept to pay for the fuel and trouble of the sea trial....
although it commonly is, you should never
expect the boat ride to be free just because you decide you dont want to buy it.
also, understand clearly that I said a PRE-determined amount, that needs to be agreed on.
I wouldnt give earnest money until you are absolutely SURE you are buying the boat, and you need the seller to take it off the market and hold it for you, for a some amount of time, so you can gather the rest of the money to complete the purchase... if you dont meet your end of the agreement within that time, you lose the money and the seller still owns the boat to sell to someone else.
and short of the lake being frozen over, snow shouldnt stop a sea trial.... and you may not need a sail, but definitely a good run on the motor under full power for an good length of time... listen and look at and around the motor with a flashlight while it being ran, and feeling if the gear boxes are getting too hot... this could tell the condition of something you cant see
there are so many things that can go wrong during "the first rodeo" that I would not forgo any of the available options to insure you arent buying a boatload of hidden problems... and there WILL be some, but you want to avoid the expensive ones.
and even though most surveyors are on top of things, they are only human and can miss stuff, so the more time and "hands on" he gets with the boat, especially one that is sailing and motoring on a sea trial, the more chances there are of the hidden stuff being found.
the bigger the boat, to bigger potential there is for it to have more problems, and whether these are small problems or big problems, collectively they will require an exponentially "bigger" amount of money to repair it all...