catamaran first timer, lee drift

[mauricec]

hey all, newbie sailor here (I've been sailing monohulls regularly since June). Today was my first attempt at sailing a catamaran -- I went down to a local rental place and took out a 16" Hobie Cat Getaway, but ended up having some trouble with it.

To setup the situation: the rental place is on the east shore of a narrow channel. I'm docked on the west side of their dock, pointed north toward the lake. A light breeze is coming straight down the channel from the north. My plan to leave the dock is to go directly west on a beam reach to pick up some speed, and then head up and tack to exit the channel.

Obviously this didnt work out, or I wouldnt be posting this. We ended up pointing west with wind coming across the beam but we're not moving forward-- instead we were drifting south away from the wind (perpendicular to the two hulls), right at some expensive looking yachts. This being my first time on a multihull, I didnt know exactly how to react to this. We ended up having to be pulled out from between a few yachts by one of the guys from the rental shop!

Unfortunately, the rental folks weren't super friendly, and didn't really want to answer my questions about what happened (apparently this was the 3rd time today they had to rescue a hobie after it got stuck). Thinking about the physics of it now, it seems like it would have helped to shift our weight towards the lee side of the boat to help that hull dig into the water and hopefully stop our drift and make some headway. What would've been the right way out of this situation?

[sailingdog]

Small beach cats can be a handful if you've never sailed one before. Be aware that they can go faster than you'd expect and the sails often need to be sheeted in far more than you would on a monohull dinghy of the same size, since the apparent wind shifts further forward the faster you go.

Without some boat speed, they tend to have a lot more leeway than a dinghy would... Why you weren't moving I can't say, but it is most likely USER ERROR—probably had the sails trimmed wrong.

One other problem with beach cats is that without some good speed, tacking through the wind will generally fail, since you don't have the momentum necessary to carry you through the eye of the wind.

[sck5]

I have a hobie and it really helps to tie a piece of yarn or a short length of casette tape to the forestay or the bridle to have a visual reference for the wind. You can put some on the shrouds as well. Sometimes in narrow channels there can be odd eddies of wind that will take you aback. For example, where I live there are cliffs along the lake front which make the wind within about a hundred yards of the beach behave in strange ways.

What sd said about tacking a cat is very true. With a monohull you want to pivot it as quickly as possible in a tack - You cant do that with two hulls since there are two pivot points and they arent the same. You have to steer it through the tack in a much less sharp turn than in a monohull. Helps to give it a bit of mainsheet when you put the tiller over too.

Your notion that it matters where people are sitting is not entirely wrong since cats are sensitive to weight distribution but a getaway is much less so than say an H16 since it has far more inherent buoyancy. It is much more likely that it is sail trim that is the main problem

[mauricec]

oh yea, I'm 100% sure it was user error, I was just trying to find out what the error was

Its definitely possible that my sails were in too tight, and I can see how that could result in the behavior I was seeing -- It seems like on a cat, wind coming in at a bad angle into your sails will probably just make you slip leeward, whereas on a monohull you just arent going to move very much.

thanks for the pointers.. hopefully I'll do less freaking out and more thinking next time

[US27inKS]

When I used to sail my old H16 I found that most any point of sail was close hauled. The reason is the amount of forward shift in your apparent wind due to speed. A piece of cassette tape on the bridle is the way to go. If you start out reaching with the sails eased out, watch the apparent wind and sheet in accordingly. If you lose boat speed you'll have to ease the sheets again otherwise you'll have the wind pushing you sideways instead of driving forward.

When tacking my H16 I found it easier to allow the jib to backwind against the mast until the main filled, then pop it over. It's not the fastest tack in the world, but I never got stuck in irons.

[sailingdog]

What US27inKS said about most upwind sailing being close-hauled is true once the boat is up to speed and moving, but until then, you need to have the sails set for the proper wind angle, until the apparent wind starts to move forward due to boat speed, when you can sheet in safely.

IIRC, most beach cats don't have centerboards or daggerboards, and depend on the hulls to generate lift to help prevent leeway. If they're not moving forward quickly, they tend to slide sideways a lot.

[chucklesR]

Start on a beam reach, get moving, head up, tighten up sails. Give the boat more underwater control in light air by sitting on the low side and using as little rudder movement as you can.

[gc1111]

The Hobie-16 does not have a centerboard, it depends on an asymmetric hull to generate lift to windward to counteract the force of the sails to leeward. It has dynamic resistance to side force, but very little static resistance. This means that if you are not moving it will get pushed sideways very easily. So ease the sails all the way out and slowly sheet them in. As the boat accelerates (and it will do so rapidly if there is much wind) you gain control and are off and sailing.

Also the hull lift depends on the lee hull being buried more deeply than the windward hull.

[philsboat]

I rented a Hobie 16 on Marco Island once and I found that if you ease the mainsheet a foot or so and fall off to pick up speed just before the tack then backwind the jib as you pass through the wind you won't get stuck in irons a much.
Phil

[sck5]

also, if you arent going the direction you want and put the rudders hard over it is very easy to stall the boat if you dont have much speed