Q: My husband and I have been going boating on the Sacramento Delta since we were in college. We'd always rent a houseboat for the weekend. Somebody would bring a ski boat, someone might bring a few Jet Skis. It was always a lot of fun and, frankly, there was always a lot of drinking involved.

We have our own boat now and we still go on houseboat trips on the Delta on warm weekends with our friends. We don't have kids, but some of our friends do and they usually bring them along. Anyway, the thing is, there's still an awful lot of drinking that goes on. I'm no prude. I enjoy a few margaritas on the houseboat. What scares me is when someone who's been drinking drives our deckboat. I'm not really concerned when someone who's been drinking drives the houseboat, because I know it doesn't move very fast.

I don't want to be a party pooper, but I also don't want anyone to get hurt. What should I do? Should I say something?

Maria R.
San Mateo, California

A: Two words for you: Speak up. If one of your friend's children gets backed over by your deckboat or houseboat, you'll wish you had. A less-than-controlled boat is every bit as dangerous as a less-than-controlled automobile, perhaps even a little more so because, as you know, a boat doesn't have brakes. It only stops when its throttle is pulled back and its momentum dies.

Guess what? That big, slow houseboat does a dandy job maintaining momentum. That, and the fact that it's a massive thing weighing at least several tons, means it can do great damage to docks, other boats and anything or anyone that gets in its way. Slow-moving as it may be, a houseboat is every bit as dangerous as a deckboat (or a high-performance powerboat or personal watercraft) when someone under the influence is at the helm.

I use "under the influence" for a reason. I wouldn't want you to mistake that with "falling down drunk," "blasted" or "looped." I mean under the influence as defined by law, which in your state, California, happens to be a Blood Alcohol Level of .08 percent. That means about three beers, three 8-ounce glasses of wine or three ounces of hard liquor for a 180-pound adult in an hour. Having logged a few beer-soaked hours on the water myself in less responsible days, I can tell you from experience that it's not tough for 180-pound man to consume twice that in an hour.

You mentioned you do your boating on warm weekends, so here's something else you need to know: The warmer the weather, the greater the body's alcohol absorption rate. Translation: It takes less alcohol to reach the legal limit.

Here's another fun fact: You live in one of seven states in which a Boating Under the Influence conviction carries the same weight as a Driving Under the Influence conviction. That's right, a BUI in California counts as DUI, and in addition to leaving you SOL for a ride to work while you're license is suspended if your BAC is high enough, it could leave you with NSF in your bank account. The average DUI in California costs $5,000 to $6,000 by the time the convicted party pays his lawyers, all fines, tuition for mandatory alcohol education classes and mile-high insurance rates.

Two-time DUI/BUI losers get 30-day state sponsored vacations, something those who injure or kill someone (or just happen to cause more than $500 in property damage) while under the influence would have gladly accepted. These folks, no, felons, go to prison.

Like any potential tragedy, Mary, it all seems far away and unrealistic, until somebody, beer in hand, fires up your deckboat, puts it in reverse and backs into a swimmer. I've met a few people who've made this horrific kind of mistake. What they agonize about most isn't the money they spent defending themselves, the jobs they lost, the time in prison. Every day, they are haunted by the lives they've destroyed, including their own.

So speak up.

Q: I've always thought my bowrider does 60 mph. At least that's what my speedometer says. Then my buddy, Brad, comes along and tells me the boat probably only does about 57, that boat speedos are way off. What's the deal?

Dave P.
Decatur, Georgia

A: Brad is probably right. Boat speedometers are notoriously inaccurate, especially at higher speeds. In testing thousands of boats over the years, we've seen speedometers that were as many as ten miles per hour off, based on radar-gun reading comparisons. Only in the rarest of instances has a speedo ever read low.

So what's the deal? Some gauge manufacturers will tell you the placement of the pitot tube, which uses onrushing water pressure to determine your boat's forward speed, is everything. If the pitot isn't placed or aligned properly, or if it gets clogged with debris, the speedo won't read accurately. Speedometer calibration, matching what the pressure tells the gauge to what it actually reads, is another factor, and not all gauge makers take the time to properly calibrate their instruments. You'd have a hard time getting them to admit this, but most gauge makers would prefer their speedos err on the high side. That, too, is a function of calibration.

Though not perfect, high-quality, high- performance speedometers tend to be more accurate. They also tend to be a lot more expensive. As in most things, you get what you pay for.

Final words: Tell Brad to chill out. Fifty-seven miles an hour feels just like 60 mph. If it feels fast to you, it's probably fast enough.