Putting your antenna inside the boathouse for a test might have seemed like an exercise in futility, especially when the weather was bad, but it told me that the WVNY signal was weaker than the tvfool report would lead me to believe.
Another idea was to put the antenna, in front of the boathouse (such that it faces over the water, and such that the boathouse is not between the antenna and transmitter.
If you put the antenna in front of the boathouse you will not receive the benefit of the signal boost from the additional signal reflected from the boathouse which adds to the direct signal.
And if I leave the antenna where it is, that is such that the boathouse is between it and the transmitter, then try aiming even slightly away to one side of the boathouse, I will lose what little signal there is.
Yes, you will lose the benefit of the reflection from the boathouse that adds to the direct signal which isn't strong enough without help. But, when you aim the antenna at the boathouse you also pickup reflections of undesired signals coming from the rear.
If you can mount the antenna at the optimum height and at a location that it doesn't "see" the boathouse but has a ground mounted reflector screen that gives some signal enhancement that replaces the signal enhancement that you were getting from the boathouse, you MIGHT improve the reception of WVNY.
Your reception problem is so difficult that you need to use every trick you can think of all at the same time:
1. The most sensitive tuner you can find
2. The highest gain CH13 antenna you can construct
3. Use a preamp with a low NF for the CH13 antenna
4. Grounding the coax to exclude unwanted signals
5. Shield the antenna for Max F to B and to reject local unwanted signals
6. Mount antenna at optimum height
7. Provide signal enhancement that adds to the direct signal
8. Make sure that no objects are in front of the antenna that will pick up reflections from the signals coming from the rear
....still at the stage of just thinking out loud....