Ron - your question and your own analysis are basically in conflict. In very simple terms - the only variable cost for your boat is basically fuel (and to refer to the other post/link - beer). I assume some people here will disagree at first but let me explain this from a costing perspective. First - let's list the cost factors (not claiming that the list is complete but these are more or less the items if I don't add equipment to it):
- trailer maintenance
- vehicle fuel
- vehicle maintenance
- lake access fee etc.
- your time
Let's also assume at this point that the boat is driven 100 hrs/year and you'll keep the boat for 10 years (to be somewhat in line with your initial question/comment about big repairs at around 1000 hours).
Now let's look at this list and think what is truly variable - which is in essence fuel and your time and the vehicle fuel/mileage to tow the boat to the lake if applicable (but will leave it out for now as it won't really matter until we get to the end).
The reason that I didn't count oil and scheduled maintenance into it is simple: Even if you drive less than 100 hrs a year - you will still have your scheduled maintenance performed - so the cost will incurr no matter if you drive or not. When we talk about repairs - you likely end up over these 10 years to replace a battery, an impeller etc. and some of those you could count as variable (impeller every 300 hrs or so) - others will happen eventually but you can't consider them as variable except you would say I replace the battery every 100 hours as an example.
So let's continue now to the basic variable cost - your time and fuel. I'll assume you will drive for free - so that's easy ;-) Fuel for simple purposes = 2 gal/hr = $8 (change the number if you have an Epic to about 5 like me
). The only other variable cost which you can attribute to take the boat out is your truck if you need to drive (but eventually you'll be left with the same problem to allocate the variable truck cost to it) That's your variable cost you can truly attribute to each hour you actually drive - anything else becomes arbitrary which I will explain below.
As I said before - you will do maintenance and exchange the oil, use cleaners etc. - some in regular intervals and other things when you have time (like cleaning the boat) - so your biggest problem is to find a predictable driver (not boat driver - here I mean a cost accounting term - driver = trigger) to associate the cost with time - because you're asking for the hourly cost.
So let's put some numbers to this:
8000.00 Fuel over lifetime
3000.00 scheduled maintenance (yearly oil change etc.)
1000.00 3x impeller replacement
12300.00 over the 10 years you own the boat
As you can see - the fuel is your highest cost BECAUSE you left depreciation out. I said earlier that depreciation is not variable and some may disagree but hear me out. We assumed in my example that you keep the boat for 10 years. Bottomline when you try to sell the boat - the hours won't matter much - even if you have not driven it at all - you won't get your money back - so the boat just depreciates - even if you only stare at it. If we go linear for a 50K boat - you will depreciate 5K every year and you should put the money actually aside as you will need the 50K in 10 years to buy the new one. You obviously will get some money back for your old one (trade-in etc.) but the new boat will also be more expensive as you will see the surf gate, wetsounds etc. so chances are your 50K you put aside will barely get you something to brag about
So if you now compare the variable vs. fixed cost on a yearly basis (which is 1230 vs. depreciation which is 5000) you'll see that you're not going to make the right decision which boat to take - because your boat is still costing you money - regardless of sitting in your buddy's boat ...
and to add the car problem back into it. If you don't have a boat you may not need the big truck to tow but is the truck now part of the math or considered truly variable based on the 0.55/mile?
The only time this calculation above is not as bad is if you do this as a business (wakeboarding school etc.) - then most of these costs become much more predictable as you will trade your boats on a yearly basis etc. but that doesn't make the costs variable - but you will have a better idea how much you charge your students to break even or better make a profit.
So to conclude this: A friend of mine said one night on the boat when we talked about people chipping in for gas (or not chipping in) etc. Every minute on the boat is basically a buck. If you drive 100 hours a year = 6000 minutes = 6K which is probably what it's going to cost you with depreciation, gas etc. and that's surprisingly accurate. So if you give someone a pull - count the minutes in the future ;-)
Bottomline is: If you have a boat - keep enjoying it and never show this math to your wife - you likely won't have another boat EVER! And add more of the other variable cost: beer.