If you look at Google Maps at least on my 8" tablet it looks like there is no waterway from Siem Reap to Battambang. But the tour companies in Siem Reap advertise and sell tickets for a boat and they said my bike is OK and they would pick me and my bike up at the hotel at 7am for the 7:30 boat.
Well I was up at 6 and waiting for whatever was going to pick me up by 7 and nobody showed up. At 7:20 I was starting to think I was going to miss the boat as I knew the dock was 15kms away as I rode it when I arrived a few days before. The hotel phoned the tour company and they said someone would be there shortly. Fifteen minutes later a tuk tuk arrived with four European women and all their gear. The Tuk Tuk driver says follow me. To make a long story short I followed the tuk tuk for about 6 blocks where I was instructed to wait with what appeared to be about 30 other people. It turned out we were all going to Battambang by boat. A tour bus arrived and all of us including my bike were loaded into the bus and driven to the dock.
The boat leaves when it is full, then it takes on cargo and more people along the way. My bike was loaded on the back of the boat next to the engine, then cargo including a few logs were added to the mix.
The trip was exceptionally interesting. The waterway was one floating village after another, fishermen and a whole population that is living and working on the river.
Now I can confirm that you can get to Battambang by boat, but not this time. As we got further up the river we kept getting stuck in the mud as the river shallowed. Eventually it was pretty obvious that we would not make it all the way by boat and the captain headed to shore and tied up to a tree.
I had a quick look at a map and we were approximately 35 kms from Battambang and where the road started. We were met by three pickup trucks and all of us including luggage and my bike were somehow loaded on and we were driven the rest of the way.
I think doing the whole trip by boat is probably the norm, but it is very hot and dry here right now so the river is low. I suspect the tour company knew this in advance but? Anyway it was an experience and I met a lot of nice people.
Battambang is an interesting city. The whole country was once controlled by France, and as I rode around the city today I got the feeling that at one point some Frenchman probably decided this city would be the Paris of the East. Last night I had dinner at La Casa Restaurant. Probably the best meal I have had in Cambodia and inexpensive.
I am getting myself psyched up to ride back to Phnom Phen starting tomorrow. It is about 350 kms with two bigger towns on the way. It is quite hot here now so think the strategy will be early starts and bring lots of water.