Minimum size for ride comfort?

I am in the process of negotiating with a boatyard to custom build a power boat for me. My main concern is the ride comfort for the passengers. Currently, I have a 35' sailboat, which I love to sail myself. The problem is any time I have guests, especially women, someone always gets seasick, which ruins the whole experience. Sometimes, I have people getting sick even in near calm conditions. In about 3 - 4 foot swell, one can't move around the boat without holding on to something. Can anyone advise what minimum size of the boat I have to go for to have sufficient comfort level for people, who are on the boat for the first time without taking any medicines? I read many posts on here that say that the size is a matter of preference. But, I think there should be some objective known number above which, one can say that the first time sailor will be comfortable on the boat. Maybe, someone has charter experience taking groups out on different boats??? I am considering a larger power monohull or a catamaran. It needs to provide comfortable ride in 3 - 4 foot swell at slow speeds and at anchor. It would be a shame to spend the money and have to sail by myself again! Your opinion is much appreciated.

 

So many questions!
Type of powerboat? Center console, open? Cuddy? Cabin cruiser, salon? See & be seen speed boat with bow & aft "waving hands" seating? Trawler?
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I would want to be on a boat where I could quickly move to a more secluded area, where I might do my retching in private. Also, be able to sit THERE, in comfort until my trips to the rail had run their course. I would not want to stink up the whole boat or ruin the outing for the rest, OR have everyone watching my misery up close & personal.
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Seating also depends on the length of time on the boat. We just completed a 1,000 trip where we were @ the helm for around 10-12 hrs a day. EVERY seat on the boat wore thin after 3 days out. The 4 of us ALL wished we had our home recliners to sit in. For extended rides, the seating must be the most comfortable that $$$ & space can allow.
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I'll tell you this... typical factory boat seating SUCKS! You are right in thinking that seating is a very important part of enjoying a "pleasure" boat. Kudo's to you for thinking ahead!

 

There are many questions yet unanswered (How many passengers? How long a voyage? What speed do you want to cruise at, etc.), but given the small amount of info provided, if the boat is going to be forty feet or longer, I'd give serious consideration to a catamaran. I designed & built cats, both power & sail, for the charter trade in the Caribbean, and the ride ine even 6 - 8 ft seas was quite tolerable.

However, there is always somebody who get's seasich looking at a picture of waves, so it is impossible to please everybody. E-mail me at mmason2@eastlink.ca if you would like to discuss a design further.

 

Sea sickness can affect everyone differently, so a size would be difficult to pin down. My wooden, 63' ketch, which I chartered in the Caribbean for a number of years, didn't experience much difficulty in this regard, but there were occasions that someone would get ill.

Many things can affect the likelihood of this. Drinking, remaining below, not being able to focus of a specific task, some types of food, physical issues, genetic disposition and mind set can all cause someone who normally wouldn't get sick to become sick on an outing.

Some people are just more likely to get sick then others.

Things to look for in another yacht would be a D/L of 250 or higher. Also boats with not so high a ballast/displacement ratio, will help.

Many modern craft have a pretty quick roll moment, which doesn't help things. These boats are usually pretty fat butted too, which can increase the yaw tendency in some conditions. Look for a full bellied yacht like an older Island Packet or Cabo Rico.

In the end experience, personal preparation and life aboard will govern who will get some motion discomfort. The key is to nip it in the butt, before it's an issue, because once the cycle is started, it has to run it's course. Wrist bands, medication, a boat with a comfortable motion, keeping the guests busy, limiting drinking, not permitting someone with a hang over aboard, eating habits, etc. will help, but you'll always run the risk, because ther's only so much you can control.

 

Thank you for all the feedback! Good point about having a secluded place for retching, btw. To answer the questions, my design is not done yet, but I’m leaning towards a cruising power catamaran with two or more state rooms, main saloon, and open or enclosed fly bridge. Most of the trips will be only a couple of hours at 8 to 15 kts with up to 10 people, and a lot of time at anchor. I guess what I had in mind is the worst case scenario, when you have a girl, who is the first time on the boat, was drinking the night before, and didn’t take any motion sickness medicine (if you invite a couple, and the girl does not have a good time, the guy will not have a good time either). I know on cruise ships, not many complain about motion sickness. On my boat, almost everyone gets sick. So, is there some reasonable size in between that 99% of people would not even get a hint of seasickness, or is it just too large and prohibitive to build? I am also still not sure about going with a catamaran. Is the two-hull design more comfortable at all boat sizes, or is there some size, beyond which, a catamaran does not offer any comfort advantage? Most commercial passenger vessels or large yachts are not catamarans.

 

Good luck - sea sickness will occur on any and all boats! The only really effective method is to leave the boat tied up at a sheltered dock - and even then some people will feel queasy!
Effective sea sickness pills were only resaerched during world war ii, when many sailors had it chronically. They were on veeery big boats - much bigger than most of us can afford.
The BIG factor, is if the visitors actually take something for sea-sickness in plenty of time. You almost need to watch them take it, especially kids, as many people are averse to pill taking.
Previous advice about diet, weather conditions etc, is extremely pertinent.
One hint I can give you, a sea sickness preventative that seems effective 95% of the time - keep the tips of your or guests fingers in a cold airstream. I was first told this as a kid on a bus trip. By sticking my fingers of one hand out the bus window as far as the first knuckle, my nausea went.
Years later on a boat, I tried this with other people. You cant really stick your fingers out a window, but tell them to hold onto a railing or edge that is on the windward side of the boat- seems to work a treat.

 

Keeping the knuckles cool in a cool air stream only works if you stick your tounge right out and balance a spoon on your forehead, Works for me!!

 

Interesting. I thought planning hulls or semi displacement were less comfortable than full displacement. Can you explain about that?

I don't know if I should use something new like that, but what about wave piercing or foil assisted cats? Would any of that help to have a steadier ride or better speed and range? My objective is to have a vessel with long range and good economy at slow speeds, 8 kts or so. But, it will still be nice to have a high speed capability on short trips.

 

Re wave piercing catamarans - I have travelled on them and displacement ferries. Was never as sick as on the cat.
So was everyone else, and they discontinued the cat service across Bass Strait after two seasons.
They certainly rolled a lot less, but the constant veering and dipping caused by the water jets doing the steering made even a calm crossing real upchuck material.
I have never travelled on a foiler, but seeing films of them travelling in really rough seas in the mediterranean was very impressive.

 

"Most of the trips will be only a couple of hours at 8 to 15 kts with up to 10 people."

The USCG requires a far different vessel to risk over 6 folks at a time .
If these folks are going to PAY for the priveledge you will need a license and the vessel will need to be built to USCG specs.

Fire retardant resin (if GRP) collision bulkhead and proper bilge pumps as a start.
The CG will need to review the plans before any building is done , and will come by at times .
Google USCG Subchapter "T ", and be prepared to follow the requirements to the letter.

Have you looked at the USED market ?, you can usually save 50% to 80% if a production boat will fit your needs.

Look in "Boats & Harbors" for the boat of your dreams , and save 2-3 years of building, outfitting , testing.

FF

 

What's up with Cat lovers? Catamarans seem to hold a spell over some people that I, frankly don't understand. Just like 7 bar jazz, I guess it's a beat that is only soothing to some.
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For my money, they have more "issues" than rewards & jazz sounds like every instrument is on a different tune. NOT knocking either, but I just don't see the allure to either. I must have a simple ear & a too practical eye.
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Sea sickness has so many causes that combine, there probably no way to design a silver bullet for it. Some can't ride in the back seat of a car. Others are sick 1 day out & then get their sea legs. Others do OK as long as they see a horizon. Some are set off by diet or drink, & still others can't put their ear up to a sea shell @ home. I say don't design a boat to prevent sea sickness but design it to deal with it. Lots of rail space & wash down scuppers

 

Keep the boat & go cruising solo to meet a seaworthy crowd, or sell the big boat & get your fix on a "beach" catamaran as they are fun and easy to launch solo & keep at home.

 

Having recently crossed the English Channel on the huge and high speed cat ,"vomit comet", I can report that neither size nor number of hulls guarantees a smooth ride.

 

The most comfy ride is on the BIG boat called land.

You could of course have this boat with LCD screens on the windows which looks like you're on the sea - have nice calm weather all year round, the dolpins and whales will be there consistently every time, and somewhere in the trip you could even have some scene happen where your experience and bravery saves the day. Be a hero every day