The slow fast boat to Siem Reap

Easter coincided this year with the Khmer New Year. A colleague, whose wife's family comes from Siem Reap -- the town nearest to Angkor -- invited me to go with him to see some ruined temples lost in the jungle a few hours north of the touristed sites.
I opted for the "fast" boat from Phnom Penh up the Tonle Sap river and lake to Siem Reap because the luxury coach (7USD) promised five hours of karaoke videos, whereas the boat (25USD) offered six hours of sunbathing, watching the fisherfolk and water bufalo going about their business.
The monotonous high river bank is punctuated by the occasional Buddhist pagoda and mosque (this is Cham country - the Khmer Muslims that Pol Pot did his best to exterminate).
Three hours out of PP the engine broke down. After forty minutes of banging and swearing in Khmer, the engineer managed to knock it back into life.
An hour and a half later, we stop at a small jetty and there is talk of switching boats -- this is the dry season and the river is too low for the fast boat--but we set off again. Twenty minutes further upriver, we stop and wait. By now the temperature is well into the thirties. We wait some time before a small river boat chugs up, fully charged with scorched-looking barang (foreigners). The passenger exchange is a miracle of Khmer logistical skills. Some elderly American passengers, emerging from the cabin, look as though they were expecting a Cunard cruise ship, in their white plimsols. We are an hour and a half from our scheduled arrival in Siem Reap. Four and a half hours later, we limp into port--if that is the correct term for the dried-out mudbank that a tugboat hauls us onto to disembark. Most peoples smiles have waned as sunstroke threatened. Thank heaven for the krama - the ubiquitous multi-purpose red checkered scarf, which saved me from heat exhaustion and sunburn...