These comments, below, refer specifically to trailable trimarans with accommodation and, I hope, help explain why I think trailable catamarans are better. However I do think that open deck day sailing trimarans have great advantages, which is why I have designed several under 20ft. See my Strike design pages for more

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Some one sent me the following email:

I am an aircraft engineer currently working on composite aircraft design and stress analysis. I am also an amateur boatbuilder. I recently built a 22ft trimaran and I am sailing it as much as possible. I enjoy racing and cruising.

I did a lot of racing in the past on the Fireball dinghy. I built 8 of those in ply-epoxy and love the material, but for the trimaran I went full composite.

This my first multihull and this is a pleasant change from monohull sailing. I enjoy the speed and trailability.

Since I almost never sailed on multihulls before, I thought that they were more or less equal, like most monohulls are. I read books on the subject and surfed the net for information. I now realize that a trimaran has a lot of bad features that maybe the catamaran does not have.

Let me start, in the order that they appear on my notes:

1-When raising the rudder to clean it from weeds, the boat broaches almost instantly. A cat has 2 rudders so they can be cleaned one at a time to keep control. This is important when broad reaching fast in big waves and you just crashed into a big weed patch.

2-The boat flip-flops from side to side when the waves come from the side, and the floats slam the surface of the water. This is very annoying, as well as dangerous. The float can wack on the head a man swimming around the boat. I experienced that myself when swimming in a dead calm when a motor boat cruised by. When you prepare the fenders, you fly up in the air and down in the water, all that with no lifelines, over and over at each wave. When the wind is light and you are steering the boat from the weather float and a motor boat makes a big wake, beware of the slamming and the spray!

3-The tiller extension is in the way constantly and there is no convenient place to store it.

4-The boat pitches a lot (hobbyhorsing). The floatation plan inertia is small compared to the overall boat moment of inertia. This is annoying and pulls the propeller out of the water in waves.

5- When steering from the cockpit you need to bend your neck at 90° upwards to see the sails. On a monohull, the cockpit is usually wider and because the boat heels it is easier to see the sails. When you steer from the nets it is easy to see the sails but you are exposed to all the spray and float slamming plus you cant see the compass. I guess I could mount compasses on the floats...

6-There is no privacy when using the toilet or getting changed.

7-The floats are useless volumes. They are always at 100% humidity inside and are almost impossible to inspect.

8-It is impossible to turn the tiller to make sharp turns when you sit in the cockpit with your hand on the outboard motor throttle.

9-It is impossible to open the pop-top when the mainsail is lowered on it. You have to remove the boom and sail and store them on the nets.

10-It is impossible to walk all the way to the float bows to jump on the dock, install fenders, mooring lines or fix a bridle to the anchor line to prevent the boat from sailing at anchor. This could be solved by using more nets, but they are really expensive. I could go on and on it seems.

Tell me, do cats have all these undesirable features?

In my mind right now, the only 2 advantages of small trimarans over catamarans are: 1-Folding ease 2-Wider cabin for equivalent weight and cost.

I replied:

"You seem to have got most of the drawbacks on your list. Drawbacks that don't usually apply to catamarans. I haven't sailed the design you built, but I have sailed extensively on Farrier and Dragonfly trimarans. (I have also sailed Fireballs, but not for years. Peter Milne sailed with me on my Sagitta)

1) I agree weed is a problem. We got into a real tangle at 2am when racing a F31R in the VanIsle 360 last year and we hit weed just as we were hoisting the spinnaker. On Tucanu we have a strip of cedar about 1.2m x 100mm x 10mm profiled like a rudder that we use to clear weed. It has a hook on the leading edge. It has far less drag than a boathook and works well. I prefer semibalanced rudders over dinghy style ones. The latter I use on Wizard, Strider and Janus. Of course they are easy to kick up when sailing to clear them. The semibalanced rudders can be lifted when sailing , see my FAQs page for more. So yes 1) is a win for catamarans.

2) Also a win for catamarans. I guess you have seen the Costner film Waterworld. There is a good shot in it of the outriggers flopping from side to side. It is also very dangerous in a big sea of course.

3) Also a win for catamarans. I usually use two telescopic extensions (made from telescopic boathooks, much cheaper than the real thing). I can steer from either hull so have a good view of the sails (or dock when coming alongside under engine) or from in the cabin.

4) This will vary according to the design. The Dragonfly is a much nicer seaboat than the Farrier, possibly why they are more popular than Farriers in Europe. Poorly designed catamarans can also pitch and hobbyhorse. Usually because the Prismatic Coefficient is to low (some people think it should be the same as a monohull, it should be much higher)

5) This is getting boring, another win for catamarans. Also the tri cockpit is very small and it is very scary getting out to the nets when it is rough. Seeing the sails is very important to me, that is why I prefer tillers over a wheel and don't like a Bimini. On my new Romany I will be fitting a bimini as we will be tropical sailing. But only over the central cockpit area and wheel. There are two tiller extensions fitted so I can disconnect the wheel, steer and view the sails from the hulls. The best of both worlds.

6) The cuddy used on Wizard and Sango and also the removable one I fitted to Tucanu makes a HUGE difference to comfort on board. I recently sailed Tucanu as an open deck boat for 2 days in the rain. We'd sailed with the cuddy for 4 weeks earlier in the year. I don't know how I managed on an open deck boat before (maybe because I was younger) You can see more on my Plan Updates page and videos.

7) agreed

8) And there isn't really room for two people in the cockpit to handle engine and tiller separately

9) You can see from the Tucanu and Wizard photos that we can use the poptop with the boom in its normal position. I have drawn the boom cocked up on all my recent designs. More headroom aft, more space for a tack downhaul and the topping lift and lazy jacks automatically loosen as the sail is hoisted.

10) and the nets can trap water

So overall, a big win for catamarans

The Wizard/Sango/Tucanu style cuddy solve most of the folding problems on small catamarans and, because you can also sleep/cook/toilet in the hulls, they have a lot more room and privacy than the equivalent trimaran

It takes about 40 minutes for 2 people to have a standard Strider ready to sail from trailer. (A test was done in front of a magazine reporter). The Wizard is a bit quicker than that (ditto) "

And then this, written in April 2017 and first published on my Forum

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There are several things to consider. First - how often will you trail? If only once or twice a year then a flat bed trailer and launching trollies work well. They also are good if you are launching on a beach (like I did in Cornwall and also in Canada). So we used a flat bed trailer and trollies and found it ideal for us. The trollies came with the boat (a Merlin) and I modified them by fitting turning front castors (when we got them they were fixed which made steering almost impossible). Even so, I wasn't able to get suitable big tyres so it didn't work too well in sand

As you know, we had our Skoota towed at full width (3.95m, 13ft10in) 2700 miles behind a pickup truck from Everett to Port Aransas. No problems once the wide load route had been decided. The delivery driver simply used some 6in x 6in timbers across his standard flat boat trailer base and ratchet clamped them in place. That worked well

I have also used a telescoping trailer with Striders and Gwahir. That does allow one person to assemble the boat and is best suited for those who trail often as it is obviously more expensive than a flat bed

However overall boat beam is a problem (the Turbo Striders were marginal) as the trailer had to be road legal with the arms in and enough arm remaining for support when they were out

As always a twin axle is better. Different countries have different towing regulations, the US is much stricter than the UK regarding towing capacity. Not sure why, probably from truck makers input trying to make people buy oversize cars. So I cannot discuss that in general terms. Nor can I draw a specific trailer as a) I am not a trailer designer/manufacturer and b) every country is different. So all I can do is make sketch suggestions

Of course the Wizard/Sango/Skoota 20,24 have a different system. But all have hulls under 4ft (1.2m) high so they can fold under for transport. That is otherwise a good system as it requires no heavy lifting or winching.

The Strike 15 has forward hinging beams. I prefer it that way as it is fail safe (several aft swinging Dragonflies have folded when sailing after a wire failure) The Strike 16, 18, 20 fold vertically and although there are some bigger boats that fold that way I think 20ft length is the sensible limit

As far as the assembly is concerned. The original Strider and Janus had part tramp/part solid cockpit floors. To save weight but also to make assembly easier. However many people didn't like the "soft world" and prefered a solid cockpit. Those designs (and the Gwahir, Merlin, Skua) also had small mast beams. But in practice a deep beam as used on the Shadow, Eagle etc is more reassuring and results in a drier boat. So many people prefer it. I do, and accept the extra weight and trailering complication

In practice: Lilian and I did once assemble a Strider Club by ourselves. But the one piece grp cockpit/mastbeam was challenging to lift in place. The Eagle has a separate mast beam and two part cockpit floor. The mastbeam is similar to that used on the Merlin. Jetti and i could fit it ourselves, but the offset CofG because of the anchor lockers made it awkward (just a warning). The Strider Club had a one piece moulding to keep costs down. Few owners actually trailed theirs (we did). The last time I assembled a Strider Club from a trailer it was on launching trollies on a slipway. Three of us did it no problem. 2 men and one pregnant woman

Assembling a standard Strider/Merlin/Gwahir is easier as there are more parts so each is lighter. So I expect an Eagle to be between a standard Strider and a Strider Club/Shadow. The trailer choice depends on your own circumstances. I have also helped assemble Farrier 24/28. It isn't as quick as he implies, in part because the mast raising is harder with a tall mast.

Having said all that, the quickest I have ever got a Laser rigged and in the water is 10 minutes, my brother who has sailed one 3 times a week for 30 years usually takes 20 minutes.