Cat vs Mono for ICW

What are the pros and cons of an outboard powered displacement speed catamaran for Florida ICW cruising? There is lots of info on a sailing cat vs mono, but little on a displacement hull design. I am not talking an aluminum pontoon boat, but a boat designed with good hull shapes.

Cons:
Less displacement for a given length and beam.
More wetted area for a given displacement.
More time and materials to build.

Pros:
A more stable platform.
Larger useful space for a given displacement.

I don't have a feel for what happens when the going gets a little rough (crossing some bays or inlets with a 30 kt wind blowing). I have no cat experience at all.

Would appreciate your adding to the lists.

 

A friend cruised the ICW for years on his trawler and had a great time.
Then they were guests on a power cat and with the ability to beach it/not worry too much about tides, opened up multitudes more anchoring spots.
Now they are looking for a power cat.

However,dockage will be more $$$ and one can't just anchor anywhere they want near population.
There are many here who know much about the ICW and FLA.
Good luck

 

I guess I must add beaching ability and less draft to the list of pros.

Cons:
Less displacement for a given length and beam.
More wetted area for a given displacement.
More time and materials to build.

Pros:
A more stable platform.
Larger useful space for a given displacement.
Beaching ability.
Less draft for a given displacement.

 

Another con would be above deck enclosed structure would have considerably more area for wind affect than a monohull.

Cons:
Less displacement for a given length and beam.
More wetted area for a given displacement.
More time and materials to build.
Higher superstructure exposed to wind affects.

Pros:
A more stable platform.
Larger useful space for a given displacement.
Beaching ability.
Less draft for a given displacement.

 

I bought these plans from Glen-L http://www.boatdesigns.com/28-Bear-Cat-Cuddy-power-catamaran/products/779/ I reduced the beam to 8'-6" so I could trailer it in any state with out any permits. I also added a small center sponson in the rear (centered) so I could operate with a single engine. This sponson directs water to the prop. Have not built it yet as other things have entered my life. I put a full cabin on it with sleeping for 5 indoors, full bath, kitchen, sofa, etc. 6'-8" head room and a rear deck of 6' x 8' Final plan came out great and windage should not be a problem. It is a planing hull though. Designed by Ken Hankinson, a Naval Architect.

 

Can you elaborate on how this centre "sponson" directs water to the prop ? These kind of hulls generate plenty of aerated water in the tunnel, which isn't a healthy diet for propellors.

 

There are a lot of pluses for the fast displacement cat, imo. When I say fast, I mean 15-25 mph, beyond that things are not so attractive, mainly because the drag escalates. Probably the main reason they did not figure prominently in the past is they are more weight sensitive than many other types of boats, and don't lend themselves readily to say, solid GRP construction. By the time all strength and rigidity requirements are met, you'd have a boat that was already heavier than desirable. Take a look at this site:

http://www.sailingcatamarans.com/index.php/designs/6-powercats/190-skoota-power-cats

 

If the cat hulls are above, around 12/1 L/B ratio at the waterline, it's likely it would have less resistance than the mono.

 

Big nasty chop in the Sounds... not the best conditions for a lightweight multi.

. Multihulls are difficult or impossible to berth in a marina.

Not possible to handle a multihull with a trailer behind your car when its time to end the season.

Multihulls only perform well when they are kept light. Cruisers are always heavy...fluids, dingy, anchors, BBQ, Beer.....

 

The fact that cats don't flop over at an angle when the tide goes out in shallow water is a significant plus imo.

 

I see no significant difference that couldn't be offset with other features. A shoal mono can stand bolt upright and several of my designs do, when aground or beached. Slip and berth fees are a consideration, though if this is the deal breaker, you need another hobby.

Simply put, either design approach can work successfully, if well matched to a reasonable SOR initially or as a purchase.

 

OK, when dealing with a client on defining the SOR, it always helps me to narrow down the field.

You are from Michigan, how do you plan on getting the boat back and forth? Where will you keep the boat when you are back and forth between MI & FL?

What square footage of living space do you need? How much gear, weight, do you need? 2,000 pounds plus consumables? Fuel, Water, Food, Sewage?

How many people is the boat for?

Does anyone in your crew get motion sickness? Sea sickness?

Will you sleep on board? Eat on board?

What length boats have you piloted in the past?

What do you think about Hurricanes?

What do you think about rain in the sunshine with no wind?

What size boat would you be comfortable with today, if someone just gave you one?

Which of the style boats would you be more comfortable with?

OK:

You mention Florida ICW. So, I don't think you will be navigating the ICW, just the Florida section.

Key features that are important.

A lot depends upon design. A powered monohull can draft about the same as a cat. Usually, cats draft less than monos.

However, cats usually produce less wake, and usually handle wake a little better than monos.

You need great visibility. Along the Florida ICW, markings may be interesting. You do not want a boat that sits so nose high you are worried you will miss your cutoff, or go the wrong direction.

Cats give more redundancy.

Monos don't pay for the extra redundancy.

Do you prefer the layout on monos or on cats? How about your crew? How do they feel about the differences?

People who experience motion sickness tend to prefer cats over monos.

How far into the Gulf/Atlantic will you venture?

Are you a photographer? Cats are a better platform.

And the list goes on, and on.

 

And of course...How much money do you want to loose ?

A mono takes a decent wedge of cash and its all gone by the time you sell it

A multi takes a double decent wedge of cash and its all gone by the time you sell it.

 

I give up, what should he think about that ?

 

It is Florida.

I forgot to ask about waterspouts .... and lightening storms. Florida is capital of all three: wonderful humidity, storms, and calamities.

But, we should get the boat finished first.



I guess I could add, heat and humidity collide in Florida and the results are spectacular storms and unreal heat.

And I grew up on the ICW .... just on the good side.

PS, I will add, that if I did not make sense, that is because I only got 2 hours of sleep yesterday from 1pm to 3pm. And I am now having breakfast.

Oh, the wonders of government experiments upon the human body. Ask me sometime what I really think about ObamaCare.