General Questions for a Catamaran

[akprb]

Wise :-)

If you are in the Chesapeake you have such great opportunities to crew on local racing boats. If one wants to learn a ton in a condensed amount of time this is the way.

There are many classes including cruising class and the people are generally friendly (if a bad rep you'll figure it out quick)

As to budgets, never been a fan of the word. We've cruised on an absolute shoestring and with abundance. Either way we had a great time and some argument that the shoestring was better.

Lots of resources on this site for sure! Enjoy:-)

[duefocena]

Originally Posted by lindabarzini

I am coming from a 27 Hunter with terrible sails, a terrific 1 cylinder yanmar, and leaky hatches that are difficult to replace because the trapezoidal shape is no longer made in that size. It also had an odor problem.

I am looking into a Catamaran because of qualities of speed, no heeling, and decent living space. My dream would be a used Lagoon, Nautitech, Catana or Leopard, but with the crash in the markets, it looks like a Gemini is the best option.

Here are some questions. Any advice or recommendations are appreciated.

1) If I need to replace the sails, I am thinking of a 135 Genoa, Screecher, and Mainsail made out of premium woven dacron from Mack Sails. (price $2k, $3k, and $2k + $800 for Mack Stack). I think Doyle and North Sails may be a bit pricey. Any other sail choices or manufacturers? I am interested in durability over performance.

2) If I want Air Conditioning on the boat, do I need a generator like a Honda 2000i? How are marine ACs generally powered when not at the marina?

3) If I want to run nav station gear, laptop, lights, fan, and fridge all day, how much wattage in solar panel capacity is recommended? Is 600watts good enough? Are 2 house batteries (deep cycle) + a starting battery good or is 3+1 definitely better?

4) Should boat + fixes/upgrades only constitute 50% of the budget? The other 50% would be provisions, dockage, diesel, repairs, entertainment, etc.? Or can I spend up to 80% on boat?

5) If I buy a used boat and want it to shine, can the gelcoat be buffed to remove dock rubbing marks and other marks?

6) Can the steering wheel be replaced with a larger one if there is room?

7) Pros and cons of an inflatable dingy vs. plastic shell (like a row boat)?

8) Can the propane storage locker hold "normal" size propane tanks. I exchange tanks for my Weber grill, it seems easier than re-filling.

9) Are most surveyors good with Cats or do I need a specialist for the survey?

10) How much should I expect to pay for a water maker and what is a recommended model?

These are the top 10 questions I am currently researching. Any experience, recommendations, or advice is appreciated on any of these questions.

Hi Linda~

My two cents as a cat owner:

1.) Hyde sails makes great sails and were much cheaper in my experience. I assume you are talking about the Hunter as cat sails would cost much more than you are quoting.
2.) Get a small cruise air unit and the Honda will work. Remember that if you have a diesel you will now be carrying extra gas for the generator as well as the dinghy outboard.
3.) 600w is enough but you won't get that out of a 600w panel. Shade, heat, inverters, will eat it up. Go with double that 1,200w. The difference in size of panel and cost is not significant. Three house at minimum and one for the starter. If you're going to add weight make it batteries and anchors.
4.) Spend more on the boat. You will always have "enough" to do the other things somehow. Starting with a cheaper boat is a bad recipe.
5.) You can color sand gel coat with fine ( 1,500 grit) wet and dry sandpaper and a drop of dawn liquid. Polish afterword. Scratches will not come out nor will spider gel coat cracks.
6.) Any size wheel can be used short of it interfering with access.
7.)Inflatables should be called "deflatables" as that is what they all eventually do. They don't row well when the outboard breaks down , ( and it will), and they are popular to steal. Hard shells can be used for storage with a tarp over them without fear of puncturing, can be left in the sun without harm and can go over a reef. ( I have a 12'inflatable as I carry too many people for a suitable hard dinghy). The " you can roll them up" argument doesn't fly with me because it is a PITA to do. If you go rubber go hypalon as PVC dinghy's turn into goo in the sun.... Who's plan was that? Did they think you would only use it at night?
TIP: Use super glue to fix small puncture holes. No patch, just a drop, holds for years.
8.) Get smaller aluminum propane tanks ( I have two 5 gallon ) the Home Depot ones rust and are too heavy to lug around to get filled. Don't count on exchange.
9.) Get a surveyor that does cats. Get a list of the ones he has done like the one you are looking at and make him give you the name and number of the people who's cats he has surveyed. Go to a charter cat place and ask them for a cat surveyor. He works for you....or not, so command him to do what you want. Don't be mesmerized by his knowledge. The last time most surveyors surveyed a cat was "never".
10.) Go big or forget it with the watermaker. They cost a fortune but if you want to shower daily in bliss get a 5 gal per hour or larger. If you want to brush your teeth and steam vegetables bring a Jerry jug and hope for hoses.

Go....go soon. Don't wait. There are way fewer that follow through than are "in the process". There is no perfect boat. Look at older Prouts/ Geminis, get one and go. You will look back at that being the best "advice". Good luck !

[805gregg]

1.) Buy a boat first then worry about sails
2.) No A/C
3.) Depends
4.) ?
5.) Do some research yourself
6.) WHY
7.) ?
8.) ?
9.) Find a boat first
10.) Google first

[Cherise]

I think your questions would be better answered with the details of where you are going to cruise, will you marina hopping or just once a month, how handy are you etc.
But here goes, I have a large monohull (owned smaller too) but I want a cat for your reasons as well, so I too have been spending years researching your questions.

1)Minnies in SoCal has never been a let down.
2)Spent a few weeks in 90-103f and the only time I wanted A/C was when in the slip. So I think it depends on what you are doing (living aboard, cruising from one marina to the next or what most cruisers do, stay on the hook 85%+). I can confirm that a Honda 2000 powered a household swamp cooler. I would spring for the 3000 though. Hondas are the most quiet.

#4 thats such a big question. Like I asked above. Are you a total handyman? Staying at anchor? Are you a big drinker? All that matters. So far Ive only cruised months at a time, so I can't answer this, other than parts really are more expensive than house/car parts and shop around (ebay, craigslist, make a friend with someone who works at west marine).
5) It's amazing how boats can be brought back w/hard work and great products. However, the prettier she looks often the more you worry about something hurting her complexion and you may miss out on some fun (rafting up, going out that day since its heavy air and you dont want to scuff when you dock coming in, etc)
6) I think I get why you asked, maybe just add a knob.
7) Both! Main dinghy is a row boat, that can sail too, dinghy sailing is the best. And can fill that sailing hole you may get when going from mono to cat. Yes, it makes a great storage unit too. You'll probably want an inflatable for rougher days or large surf landings. The latter also for long trips, it can be too slow and rolly in the RB.
9) Always hire the best w/lots of refs. However, I know a surveyor with the highest licensing and been doing it for many decades. He's had two boats, that I know of, sink under his care and he missed all kinds of stuff too.
10) I think this depends on your cruising definition and how long you really think you will be cruising, and where to. It's so expensive and if you are planning on being in a marina once a week, for provisions, guests, land excursions, it seems like a waste a money. Lots of people out there on both sides. Payload is a cat issue though. But would you rather spend that $4k on slips more often and for food and drinks at the bar?

I suggest you start reading latitude 38 to answer these questions. Check out the archives. I am sorry, but all too often forums can only do so much. L38 shares the good and the bad (not much there!) of cruising with detailed letters from people who you know for sure are actually out there doing it, in all kids of boats, at all ages with whatever sailing skills.



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[hamid39]

Hi every body
I have a question about catamaran trolling motors but I’m not sure if I’m asking in a right place or not.
If here is not a proper place please guide me the right place.
Anyway I constructed my own catamaran boat and I used two electrical trolling motors which are exactly same for propelling. Everything seems good except these two same motors. My question is here “should I use just same propellers or one of them must be CW and the other CCW??? “
I’ve changed the rotation direction in one of the motors, but the propeller itself should be changed too i.e. we need CW and CCW propellers.
I appreciate any help
Thank you

[valhalla360]

Originally Posted by hamid39

Hi every body
I have a question about catamaran trolling motors but I’m not sure if I’m asking in a right place or not.
If here is not a proper place please guide me the right place.
Anyway I constructed my own catamaran boat and I used two electrical trolling motors which are exactly same for propelling. Everything seems good except these two same motors. My question is here “should I use just same propellers or one of them must be CW and the other CCW??? “
I’ve changed the rotation direction in one of the motors, but the propeller itself should be changed too i.e. we need CW and CCW propellers.
I appreciate any help
Thank you

While counter rotating props would be better, with the wide beam of a catamaran, it's much less of an issue. Not sure if they offer trolling motor props in both types.

Unless you are having handling issues, I would probably call it good.

This is much more of an issue on twin engine boats where the motors are close to each other and prop walk can outweigh the effect of the motor being off center.

[Factor]

Originally Posted by hamid39

Hi every body
I have a question about catamaran trolling motors but I’m not sure if I’m asking in a right place or not.
If here is not a proper place please guide me the right place.
Anyway I constructed my own catamaran boat and I used two electrical trolling motors which are exactly same for propelling. Everything seems good except these two same motors. My question is here “should I use just same propellers or one of them must be CW and the other CCW??? “
I’ve changed the rotation direction in one of the motors, but the propeller itself should be changed too i.e. we need CW and CCW propellers.
I appreciate any help
Thank you

Counter rotating props are not required, in fact I would defy anyone to tell the difference between a boat with and without them.

[belizesailor]

Hmmm, 1 post, trolling motors, really?, do you use those motors for trolling?

[hamid39]

Thank you valhalla360 and Factor for your consideration. Let me explain my situation a bit more.
We have constructed a catamaran with these characteristics: weight= 600 kg, length of waterline (LVL)= 4.2 m, beam between hull centers (BCB)= 1.75 m, beam of one hull (BH)= 65cm and etc. . This catamaran has been designed to be an autonomous research boat so proper installation of motors and propellers is a crucial aspect in modelling and control of the boat. Because when we use two same trolling motors they produce a little lateral force which cause the boat to change the direction. Currently we compensate this problem by changing the angle of the motors with respect to the boat (a fix angle). However setting an angle for the motor will compensate the lateral force just in few range of speed and in more or less speeds it will cause the direction change again. Its like I’m saying the boat go straight ahead but it turns right or left and I have to correct the direction by control system which will be more complex. The best solution for this problem is two counter rotating trolling motors which are symmetry and don’t produce any lateral force, but I couldn’t find any clue on net despite searching thoroughly.
I really appreciate any suggestion and help.

[mark_morwood]

I do not know if you can get matched counter rotating trolling motors, but I doubt it. You might be able to find outboard props that fit that are matched, but they will probably all be too big for trolling motors.

I understand why you are trying to do so, and it would help your situation, but if you are going to use this boat in any real world conditions it is going to need a steering control system (autopilot) that should easily compensate for the lateral forces induced by the props. Normally the effects of wind, waves and currents will far outweigh the effects induced by the props. Minimising the effect with angling the motors sounds like a good idea, but you probably just need to move on to the steering/control system.

[belizesailor]

Originally Posted by hamid39

Thank you valhalla360 and Factor for your consideration. Let me explain my situation a bit more.
We have constructed a catamaran with these characteristics: weight= 600 kg, length of waterline (LVL)= 4.2 m, beam between hull centers (BCB)= 1.75 m, beam of one hull (BH)= 65cm and etc. . This catamaran has been designed to be an autonomous research boat so proper installation of motors and propellers is a crucial aspect in modelling and control of the boat. Because when we use two same trolling motors they produce a little lateral force which cause the boat to change the direction. Currently we compensate this problem by changing the angle of the motors with respect to the boat (a fix angle). However setting an angle for the motor will compensate the lateral force just in few range of speed and in more or less speeds it will cause the direction change again. Its like I’m saying the boat go straight ahead but it turns right or left and I have to correct the direction by control system which will be more complex. The best solution for this problem is two counter rotating trolling motors which are symmetry and don’t produce any lateral force, but I couldn’t find any clue on net despite searching thoroughly.
I really appreciate any suggestion and help.

Ah, now it makes sense.

I dont think you are going to find LH and RH props for trolling motors, just no market for them. You might be able to adapt some other type of prop, but that could get clunky.

Vertical skegs or tunnel mounted props might help. Just a PVC tube over the props, might reduce prop walk, maybe?

Where do you plan to use this vessel? Unless for swimming pool use only you will have to adjust for many directional influences anyway. Especially true for a multihull. The slight lateral force from the motors will be one of the more minor influences in open water.

You could buy an off the shelf autopilot and let it do the steering. They adapt quite well to various influences. Waypoints, routes, and heading commands can be fed to them via a cable/network interface. The effort of developing software smart enough to compensate on your own will far outweigh the cost of a basic autopilot.

[hamid39]

Thank you all for helping
As I mentioned in an earlier post this vessel will be used as a research boat. So we need to calculate all effective forces and interactions. You are completely right about the control system which should correct the path anyway. But for modelling the boats movement we need to know each effective force separately and the propellers lateral force is somehow hard to measure and I’m trying to counterbalance this force using two counter rotation motors. But it seems there is no such thing in market (??). Anyway I appreciate your suggestions.
Thank you all again

[ObiWanSand]

AKPRB! Thanks for the words from Mr. Hayden! Finest words and philosophy I've read in a long time!

[Stumble]

Originally Posted by hamid39

Thank you all for helping
As I mentioned in an earlier post this vessel will be used as a research boat. So we need to calculate all effective forces and interactions. You are completely right about the control system which should correct the path anyway. But for modelling the boats movement we need to know each effective force separately and the propellers lateral force is somehow hard to measure and I’m trying to counterbalance this force using two counter rotation motors. But it seems there is no such thing in market (??). Anyway I appreciate your suggestions.
Thank you all again

I hope you have access to a lot of super computer time. Even simplified hydrodynamics take massive amounts of computer power, trying to quantify every force vector is immensely difficult, and even the pros typically just deal with rules of thumb, because they are acurate enough and tend to get lost in the noise.


For your application, I don't think anyone makes counter-rotating trolling motors, the market would just be very small. But if you have to have it done you can have props custom made, or you could turn the prop around on the shaft and spin the motor 180 degrees.

The other option would be internal motors driving a shaft attached to high thrust outboard props. This would be a little more expensive and difficult but doable. It just depends on how important it is to identify the forces.


The prop walk you are trying to control for however is fundamentally not quantifiable, or at least not easily. Even the mechanisms that cause it aren't fully understood. There are rules of thumb of course, but NA's really aren't sure what's going on. Though a research project dedicated to finding out would be a great service.