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Mooring a trimaran vs a monohull

QUESTION: I am coming from a monohull and considering my first trimaran. Are there any differences I should know about as far as anchoring and mooring are concerned?

ANSWER: Yes, a few things to note and prepare for. But first let me clarify that there are many different ways to moor a boat and certainly some that I'm sure work well that I've not yet tried, seen or even heard about. So please send in your own tips and if pertinent and interesting, I'll feature them in this chapter. Meanwhile, I will tell you what has personally worked well for me.

The first thing you might have to do, is to pick up your mooring! If there's plenty of water around your buoy, then practice coming in on a beam or close reach and then rounding up head-to-wind and see how far your particular boat travels. You will most likely find that a multihull approaches much faster but also decelerates faster than a monohull of the same size. It will depend a lot on whether there is a chop and how much wind, but once into the wind, the boat may not advance more than one boat length. A lighter boat will decelerate (and accelerate) faster than a heavier one whose forward momentum will help the boat carry on into the wind.

For the approach, I generally make sure the main is slackened off to slow the boat but work with the jib sheeted to retain good forward motion and steerage until I am ready to round up. Keeping in mind that I mostly do this solo (even if there is someone else on board), so I'll bring the tiller back to the center before running forward.

You'll probably find that once slowed to nearly a stop, your multihull will quickly pick up some serious side drift and soon be bearing off, sails filling and off sailing again before you had time to even think about it — so you need to either be ready and organized to catch the mooring first time or at least have a plan for sailing past it, bearing off and making a fresh approach. If you sail over the mooring buoy, try to keep it closer to the ama than the main hull. There, it will not hang up with any brackets or waterstays.

Picking up the mooring.

This will depend on how the mooring is set up but first, let me say that I almost always 'sail' up to a mooring, rather than motor. (I just find it more controllable, as having learnt to sail in England just after the war, we almost never used motors or even owned one and believe me, the narrow rivers and estuaries were packed with small boats too). If there is a small dinghy moored there already and it is low enough*, I prefer to round up and sail a trimaran right up over the dinghy, so that it passes between the ama and the main hull. I can then go on the tramp to the forward aka and grab the dinghy's mooring line (painter) as it passes under.

* I specifically recommend a low, punt shaped dinghy with straight sides and flexible gunwales. This style of dinghy is easier to 'sail over' and having straight sides, lays parallel to an ama, either outside, or inside under the tramp of a tri. In my past boat, my dinghy would lie quiet under the tramp, it's movement nicely dampened by the trampoline. The soft 'flexible gunwales' help to absorb any accidental collision shocks, without damage to either the dinghy or parent boat.

If for the first time, you're not sure the dinghy will pass under, then take it on the outside of the leeward ama, grab it's mooring line and then walk it quickly to a cleat on the main hull of the trimaran. Once you're attached you'll have time to get more organized… first lowering the jib and then the mainsail.

If it's a rubber dinghy, you're not taking much risk by trying to steer the boat so that the trampoline sails right over it, but you'll need to watch the antics of the dinghy carefully as you approach as they have a habit of turning 90 degrees just as you come up to them! If so, aim at brushing the dinghy bow with either the main hull or ama, so that it is turned fore-and-aft again where it should be.

If there is no dinghy, then take the mooring buoy between the main hull and the leeward ama. If the buoy has a loose mooring line already attached to it, you might find it helpful to use a boat hook to grab a line and then cleat it. If you really come in too fast, then you might just take the line up over the forward aka and hold it firmly down on the trampoline close to the main hull for a few seconds, until the boat decelerates and stops and then walk it forward for cleating. If your main hull is really too high above the water to reach the buoy even when kneeling or lying on the deck, then you can also pick it up off an ama but in this case, be ready to slip a line through the ring and walk it quickly to the main bow once the boat has come to a stop.

If there is only a buoy with a steel loop, then I still prefer to grab it with a gloved hand rather than a boat hook and quickly slip a mooring line through it and back to the boat. If this style of pickup will be a regular one, then I suggest you make what I call a 'clobberhook', which is a large snap hook notched and bound into a rugged wood shaft (to extend your reach), with a mooring line permanently attached (see sketch). You pre-attach the end of the line to your boat's mooring cleat as you approach the mooring and then all you have to do is clobber the ring with the hook and once engaged, you simply let go and you're moored! Well, at least temporarily… see Permanent Mooring below.

I've had a few other sailors make these clobberhooks after seeing mine, but as I almost always have a dinghy left on the buoy, I mostly used the sailover approach where I could grab the buoy without needing the extra reach.


If you really insist to motor your multihull in close quarters, expect to have a few surprises. As I've said elsewhere in this article, these boats are light and have a fair mount of windage relative to their underwater profile. This makes them tricky to keep going straight — especially when the speed is low — all very different to a heavy, deep monohull. You'll need some good fendering on the bow if coming into a dock, as it's hard to judge the stopping point. I've met some Farrier owners who swear by their system of actually motoring up to a dock by approaching astern-first — a sort of 'front‑wheel drive' approach that I can understand might work ok if you can accept all the strange looks you're certain to get. Personally, I've always found sailing in easier if there's enough space to round up and the wind direction is favorable… but I know it's not for everyone. I've always felt that a good solution for a small tri would be two electric fisherman drives with coupled controls that would permit you to back one and advance the other. That way you could literally make circles around anyone else ;-)

Permanent Mooring

Mooring a multihull, tri or cat with a single mooring line, does not work well. The combination of a light boat with nearly double the side windage, will have the boat sailing around from one extreme tack to the other, all day and night if there is a wind.

As for a bucking bronco, using a bridle will definitely help control her. I would suggest to make up two short mooring lines of say ½" nylon, with rugged bronze snap hooks on each end… each line about 70% of the total boat beam in length. I normally leave these lines attached to a sturdy eye on the bow of each ama and 'store' them while sailing, back along the ama deck. Once moored with the initial buoy line, I bring the other end of each bridle line up forward and snap the hooks on to the mooring buoy—one each side of the central line. I then pay out the central line so that the boat drifts back with weight totally on the bridle and then re-cleat the central line with 6–12" of slack, as both a backup as well as leaving it there, ready to haul up the buoy and unsnap the bridle lines, prior to casting off.     For larger trimarans, I'd recommend to use a system recommended by trimaran pioneer Jim Brown, and that employs a fairly large swiveling snatch block shackled to the bow of each ama.    The bridle then passes through that block and back to a large, solidly mounted cleat on the foredeck.   By adjusting each bridle length, one can get the boat to lay at the most favorable angle for anchoring or even when using a bridle with a drogue or sea anchor.    In a nasty sea, it sometimes proves favorable to have one bridle line shorter than the other, so that the boat is biased to one side and not eternally switching side-to-side.  So having bridle lines adjustable has its advantages, particularly for larger cruising boats.


For a short picnic stop, I prefer (on a 24–27' tri) to use a small Bruce anchor with no moving parts, 3-4ft of chain and a 38" nylon mooring line. It's simple to handle and a Bruce of only 8–10lbs has a surprising capacity. But if you're in a place where you might experience some wind while moored overnight, you might want to rig up a bridle for the anchor line too. What I usually do then is put out my main anchor of 17 lbs (plus 6 ft of chain) and a scope of at least 5 times the water depth (usually in fairly shallow water). I'll then take a bight in the anchor line and make a loop. I then snap in the hooks of my mooring bridle into the loop and pay it out until the bridle takes the anchoring load. I've found that such a loop in a relatively large diameter anchor line has never pulled tight enough to be hard to undo, so this simple system has worked well for me.   If it's windy, having a small flag tied firmly astern, can help the boat to weather vane head to wind.    Just 2 sqft can help.    For mooring overnight, running a stern line to a tree on shore is a secure way to prevent the boat from sailing around.   If that stern line is long enough, you can simply wrap it around a tree and back to the boat.  That way, you only have to let go one end and haul in the line, so enabling you to pull away from the beach without having to go ashore again.  

See also a 2020 article of Anchoring Tips (coming soon)

Casting Off

While one could say this is a reverse of anchoring, perhaps there are a few things worth mentioning. I'll typically put down all the rudder blade and just a foot of daggerboard, haul up the main first (making sure the mainsheet is loose and free) and then take in the bridle, leaving the boat moored temporarily on a single line to the bow.

Once ready to leave, I'll haul up the jib and decide which tack gives me the most space. A multihull will often drift quickly to leeward for a few feet before gaining forward motion so you'll need to allow for that. If you're leaving a dinghy on the mooring, bring the end of the short central mooring line (that's attached to the buoy) and snap it on to the mooring line of the dinghy, on the outside of what will be the windward ama as you cast off. I'll then hold the mooring line (now uncleated) and watch the natural swings of the boat on the central mooring and as she starts to bear off on the right tack, I'll back the jib. At the same time, I'll hold the single mooring line (now with dinghy painter attached) and pull it aft along the windward ama, (making sure it does not foul with any cleats) and then let go. This gives the boat a good take off and adds enough steerage way to sail off the mooring with good control.

As I said in the preamble to this article, there are many ways of doing this but this one works well for someone who is often sailing single-handed as I do.

Mooring Cleats

While trimaran amas over 20ft (6m) will generally have space for real cleats, deck space is tight for smaller boats, so here is what I suggest and use on my W17.   For sure, install a solid 6" (150) cleat on the Main Hull foredeck, as you never know when you will need a tow and this also serves for your main anchor line.   But sometimes you may need to moor at a dock and need lines attached to other parts around the boat.    For this, I prefer to install a strong S/S eyestrap on each corner of both amas.   These have mounting holes for at least 3/16" (4mm) S/S bolts or sturdy screws that can be installed in epoxy if under-deck access for Nyloc nuts is not readily available.    The eyestraps have the advantage that other ropes cannot accidentally be caught around them and they are also lightweight and take very little space.    For docking itself, you can either use dedicated 3/8" nylon mooring lines of say 12-16ft (4-5m) with one end spiced to a snaphook, or you can simply attach such lines with a bowline to the eye..   These straps are even strong enough to use with a mooring bridle, as you can still have a slack back-up line to the main cleat, as noted above.

For any sort of emergency, the strongest place to attach a rope to a boat like the W17 is to loosely loop it around one of the main beams and tie it off with a bowline.   

For more on ANCHORING, go here.


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