T&T: Catamaran vs monohull (long rant)

[Candy Chapman and Gary Bell]

First, a disclaimer:  I own and love my PDQ34 power cat.  Further, I 
think it is the very perfect boat for me, and probably for just about 
everybody else as well.  I must qualify that by adding that what just 
about everybody is doing is limited to what is commonly termed protected 
waters and/or coastal cruising.  Power catamarans with the fuel capacity 
and storm survival attributes for ocean crossing passages are all in the 
fifty foot plus range, and don't be asking how much they cost.  Truth to 
tell, the true ocean crossing monohulls are similarly uncommon, and 
similarly limited to the large and expensive models.   If you want to 
get catamaran advantages and still make blue water passages, either get 
a sailing cat, or spend some serious money on Dockwise transport. 

I also choose to limit my comments to 'wide stance' (gotta be carefull 
with THAT term now!) catamaran hulls.  These have widely spaced hulls 
with plenty of daylight underneath, and particularly have individual 
hull length to width ratios in the ten to one or better range.  They 
rely on  'slender hull behavior' to bypass the hull length wave trap by 
minimizing the depth of the wave trap trough.  By this I mean to exclude 
the power catamarans that closely resemble planing monohulls, with a 
relatively slender tunnel down the middle.  They provide some nice 
improvements on planing monohulls at speed, and some limited gains in 
interior space and such, but otherwise share most of the large engine, 
poor fuel economy, rough water handling, etc. properties of their 
monohull predecessors.  'Trawlering' isn't about those high speeds, huge 
engines, high operating costs and limited boat amenities, for most of us 
anyway. 

My Admiral insists on catamarans only, based on her experiences (similar 
to yours) on a couple of scuba charters on large sailing cats several 
years ago.   The rough water rolling immunity (as you mentioned), 
together with her desire to sit comfortably up where she can easilly see 
the horizon in bumpy seas are the main reasons she gives.  I love the 
boat motion as well, and as the PDQ sales manager said, we don't need no 
steenking stabilizers/paravanes/flopper-stoppers/etc..  The downside of 
this (that you may not yet appreciate because it is not commonly 
encountered, and is relatively easilly manages when it does happen) is 
that the slender hull, wide stance catamaran is much more sensitive to 
pitching motion than a 'wide body' monohull.  I hate to take heavy short 
period seas dead ahead or astern, because I risk some serious harmonic 
hobby horse pitching motion.  The remedy is to change course and take 
such waves off the bow or quarter, and/or change speed, or of course to 
stay home. I am talking about conditions that would discourage most 
boaters, monohulls as well as cats -- eight to fifteen foot very short 
period chop in shallow water with long fetch and steady heavy winds.   
You can think of it as trading very common mononull rolling for unusual 
condition catamaran pitching.  The conditions involved in hobby horse 
pitching are far less common than the waves that vex our monohull 
brethren -- maybe once per season or less for me at least.  Plus, the 
remedies for pitching (changing angle of attack and/or speed when 
underway, and use of bridles, weathercock sails and/or stern anchors  
are much less costly in terms of money and of fuss than the active 
stabilizers, paravanes and flopperstoppers rolling monohulls require.  

I love the maneuverability of having twin screws twelve feet apart (we 
don't need no steenking bow thrusters).  I can spin the boat in either 
direction, without moving appreciably ahead or astern.  I can pirouette 
in the marina fairway and freely choose to proceed bow or stern first. 

My boat draws twenty eight inches, including skeg protected props and 
rudders.  It is conveniently beached nose first, and will settle on the 
bottom in a very stable position.  In the yard it sits on four wood 
blocks.  I have to worry about ingesting sand, weeds, etc. when running 
generator, AC or engines in such shallow water though, and I carry a 
ladder to board over the bow on a beach.   I am almost done making an 
auxilliary water source (a plastic bucket with a thousand holes and a 
big bilge pump inside, tethered with a waterproof cord/garden hose, soon 
complimented with 'T's, valves and garden hose connectors spliced into 
all the water intakes) to dip into 'cleaner' water, but haven't actually 
tried it yet. 

I can easilly get very thrrrrrifty fuel economy at trawler speeds, and 
can smoothly and easilly get up to nineteen knots without a notable 
planing 'step' or any discernable transition in performance, and still 
get about four or five gph total consumption at speed, so no need for 
big powerfull engines, or any steenking trim tabs either.  Due to the 
exceptional overall beam (about half the boat length) I can rig 
anchoring bridles and towing bridles, or a strategically placed stern 
anchor to tame most boat motion issues -- I'm working on an anchoring 
sail with high hopes as well. 

You already have some experience with the roominess and light issues.  
Seldom mentioned is the particular sensitivity of catamarans to overall 
weight and distribution of that weight.  Best to leave those big bow 
lockers pretty empty.  Moving all your worldly goods aboard will 
similarly get you surprising degradations of performance and handling.   
Also, as relative newcomers to the market, with considerable (not 
universal!) interest among buyers, power catamarans are considerably 
more costly, and used boats are seldom found yet.  Would you consider a 
good sized sail catamaran?  They are hardly ever actually sailed anyway, 
and have, or can easilly be fitted to have most of the advantages of the 
power cats, plus 'free' propulsion if/when you are willing to sail.  
There are a bunch of sail cats maturing out of charter service at very 
attractive prices, even given their reputation as used up boats. 

Boat design and performance is a world of trade-offs.  You can have more 
of this but you must give up some of that.  I think the power catamaran, 
similar to mine, is a wonderfully optimal trade.  YMMV!  My advice:  
charter some power catamarans.  Beg rides on them (ever find yourself 
near Portland OR? email me).  Oggle power cats at the boat shows.  Talk 
with lots of owners.  Correspond with dealers and manufacturers.  Mind 
you, bring your salt shaker, you will need to take ALL of OUR advice 
with your own grain of salt.  Make up your own minds.  Let your own 
experiences and preferences guide you. 

Best of luck, see ya out there...

Gary Bell

Mervyn Carr asked(snipping by me):

I should explain further where the question comes from; <snip> I went out twice on a cat <snip>
The seas were not exactly calm, about 6' waves. I was astounded at the
difference in stability compared to my 1979 Mainship, first while at anchor
(in my Mainship it would have been intolerable) while running head on into
the waves, quartering the waves and even with a beam sea the movement of the
boat was pleasant with no sudden movements. <snip> SO, I started thinking that maybe we should be rethinking
our strategy regarding the boat we want to be on