Offshore/Blue Water v Coastal Boat

[merrydolphin]

There are many differences that have been discussed here. One that is often overlooked, even by boat builders that are supposedly designing and building boats marketed to ocean cruising is tankage. If you want to have a quick tell, whether a boat is designed for cruising or not (especially if you are in a cruising ground area. Look for the boats whose decks are lined with jerry jugs. I don’t mean just a couple cans of gas. But bunches of blue ones, and bunches of yellow ones. This is a boat where the maker did not give the vessel enough tankage for cruising, even just t the Bahamas. Especially today, with modern water makers this will run nicely on 12 volts, fuel is the biggest issue, you can make water but not fuel. ( unless you are all electric).
I was at a boat show and went aboard a 40+ foot boat being marketed as a serious cruiser. Good, what’s her fuel tankage “oh the salesman proudly said 50 Gallons” ! Well you will see lots of jugs on this one. Can you cruise this way? Of course. But that is an item that separates a blue water boat out. Good tankage, plenty of it and down low in the vessel. The reason for this is that so many boats are designed to look commodious, large and homey. So space for equipment, pumps, batteries and tanks are in your precious storage lockers. And you sure don’t want to give up that condo feel to some big yuckey tanks and silly equipment. (Like batteries)!

[rgranger]

I'd recommend you go to sailboatdata.com and look up the specs for a boat you are considering. Specifically look at the capsize ratio, the S#, the comfort number and the displacement to length ratio. There is a link on each data page that takes you to a page that explains the meaning of each of these numbers.

[cooper1991]

True. I reckon that in the longer legs of crossing the Pacific, I'd need 200-300 litres of water but assume you can catch some rainfall in squalls. No tankage for that.Water makers imho are very expensive.

[rvich]

When I was looking for a boat, thirty years ago, I found this book to be worth reading:

https://www.amazon.com/Desirable-Und.../dp/0393033112

It's "old school" now but that doesn't mean the criteria are not worth considering. The book helped me define what characteristics were important to me.

Time marches on, designs that once would have been considered extreme for offshore become more common. These days it seems to me there is a lot of effort put into speed over comfort. You will hear people tell you that a slow boat is more likely to be caught out in severe weather. However, I would consider this, having a boat that will go fast and feeling the need to push it that fast are two different things. Having a boat that is comfortable enough that you don't care if the passage takes longer is a good thing.

[Brews]

Many people would say that a true bluewater boat has to be at least 40' long. Others would say that a Cape Dory 27 is a bluewater boat (full keel, well-built).

The CSF of the Contessa 33 is 2.14, which would make it arguably not a bluewater boat. Even a Catalina 27 has a CSF less than 2 (1.86).

I had a discussion with an old sailor a while ago, and he said that the quality of the hatches determines whether a boat is truly a Bluewater vessel. He scoffed at Bomar, for instance (I thought that Bomar hatches were decent).

[kmacdonald]

Originally Posted by cooper1991

Thanks.

If I'm buying in the 32-38ft range, would a Contessa 33 OOD be a fair choice. You rightly say design decisions made on strength and reliability come first, so which makes of boat are preferable in your eyes, even down to GRP v Aluminium v Steel as well as basic design?

A contessa would be a good choice. Get fiberglass unless you are cruising with icebergs.

[Seadog56]

I am currently searching for bluewater boat to retire and cruise. I found this article helpful:

Selecting a boat for offshore cruising.

At: https://www.mahina.com/cruise.html

[RobPatterson]

You can take all the guess work out of it. Go with a proven ocean crossing vessel. Go for as much comfort as you can
https://www.boats.com/sailing-boats/1988-hans-christian-48t-7197764/

[kmacdonald]

Be careful when evaluating boats based on weight, ballast, and ballast ratios. The type and location of the ballast is at least as important. Stability curves is what you want to look at if available.

The importance of a true bluewater boat was lost with the advent of long range communication with weather reports and the reliability of weather reports. No one gets blindsided by hurricanes anymore. Get a boat the performs at least reasonably well.

[MJH]

Originally Posted by cooper1991

What are the key attributes - design or inventory of equipment differentiates an offshore/bluewater sailboat against a coastal or weekend sailboat?

How would I make a spec of a blue water sailboat so I can search for the right boat to get me across the Atlantic and Pacific in around a year?

Is a dinghy absolutely essential? Does the mast have to go through the boat or does a deck block mast fitting work safely in the oceans.

As others have said your final selection should be "designed" for ocean passages if you are going to do Bluewater sailing. That means a thoughtful design and rigorous construction to handle whatever the ocean may throw at you. My search took five years.

I built a spreadsheet of over 3,000 sailing yachts in their varying configurations encompassing the data to compute the following ratios:
SA(100%)/DISP, DISP/LWL, COMFORT, CAPSIZE RISK, L/B, ROLL ACCELERATION, and PERIOD. Note: Only use 100% SA as manufacturers frequently inflate this figure using a genoa square footage.

I then used the following acceptable ranges for those ratios:
SA/D 15-19, DISP/LWL 280-360, COMFORT 30-50, CAPSIZE RISK <1.8, L/B 3.2-4.0, ROLL ACCELERATION <.06, and PERIOD <4=stiff, >8=tender.

Select all the boats that you may consider and then take a "hard" look at how their ratios compare (sort them). Above all else, make an informed decision based on how the boat should perform on ocean waters, not on the salon's color palette. Think very hard about what is most important in sailing the boat across an ocean safely.

Beyond this there are other considerations such as tankage volumes, their location, and material of construction.

Good Luck.

~ ~ _/) ~ ~ MJH

[cooper1991]

How do you calculate Roll Acceleration and Period ratios? The comfort ratio is very dependent on LOA so many smaller boats < 40ft don't score well.

[Scubaseas]

Get a copy of John Vigor's "Seaworthy Offshore Sailboat: A Guide to Essential Features, Handling and Gear"

[wingssail]

Originally Posted by merrydolphin

There are many differences that have been discussed here. One that is often overlooked, even by boat builders that are supposedly designing and building boats marketed to ocean cruising is tankage. If you want to have a quick tell, whether a boat is designed for cruising or not (especially if you are in a cruising ground area. Look for the boats whose decks are lined with jerry jugs. I don’t mean just a couple cans of gas. But bunches of blue ones, and bunches of yellow ones. This is a boat where the maker did not give the vessel enough tankage for cruising, even just t the Bahamas. Especially today, with modern water makers this will run nicely on 12 volts, fuel is the biggest issue, you can make water but not fuel. ( unless you are all electric).
I was at a boat show and went aboard a 40+ foot boat being marketed as a serious cruiser. Good, what’s her fuel tankage “oh the salesman proudly said 50 Gallons” ! Well you will see lots of jugs on this one. Can you cruise this way? Of course. But that is an item that separates a blue water boat out. Good tankage, plenty of it and down low in the vessel. The reason for this is that so many boats are designed to look commodious, large and homey. So space for equipment, pumps, batteries and tanks are in your precious storage lockers. And you sure don’t want to give up that condo feel to some big yuckey tanks and silly equipment. (Like batteries)!

The number of fuel jugs carried on deck pertains more to the owner's expectation of motoring. We carry 60 gallons of fuel in the fuel tanks (two) and none on deck, because we can and do sail our boat much more often than not, have never run short of fuel, and that includes several ocean passages.

So if your ocean cruising boat can sail well you don't need jerry jugs on deck.

In fact clear decks is a very positive attribute for ocean cruising.

Let me go further in what capabilities I appreciate in an ocean cruising boat:

1. Rugged construction of hull, keel rudder, rig and deck. It does not have to be overbuilt or a "brick **** house" but it should be solid.
2. Tightly sealable hatches including the main companionway to keep water out in rough conditions or rain.
3. Clear decks. Nothing on deck or strapped to the lifelines, so that when seas sweep over your boat they won't be tearing items loose, and that you can move about and work freely.
4. Avoid excessive weight aloft or in the ends of the vessel, no big arches for dingy and panels aft, only light weight in the bow or stern.
5. Excellent sailing performance, including windward ability. You should be able to sail in any direction in any conditions.
6. Simple sail handling layout, meaning direct sheet and halyard leads, good sized winches, low friction (few blocks on a line) and handy and clear places from which to operate the vessel.
7. Massive storage below for spares and tools, sails, and tankage, as well as provisions..
8. Easily handled by one or two people (preferably two, for safety) meaning things can be done quickly, efficiently, and simply.
9. Windvane, watermaker, good shower (with hot water)
10. Safe galley in a rough weather, and safe sea berths.
11. Good navigation station for use in rough weather

We sail a powerful 43' 1979 racing sloop which meets all of the above criteria. We've weathered all conditions in a circumnavigation and other world cruising, and it is easy for us (to 70's somethings) to sail fast and safely. We've lived on it for 34 years. We also race, successfully, 20-30 times a year.

A good boat can do all of that.

Many would not consider our boat to be a good ocean cruising boat, but they are wrong.

Photos:
Racing mode with racing sails.
Race.jpg Views: 92 Size: 227.8 KB ID: 216375" style="margin: 2px" />
Cruising mode with dodger, windvane, and cruising sails (not shown)

[MJH]

Originally Posted by cooper1991

How do you calculate Roll Acceleration and Period ratios? The comfort ratio is very dependent on LOA so many smaller boats < 40ft don't score well.

Roll Acceleration:

=(((2*3.14)/PERIOD)^2*((BEAM/2)-1.5)*(10*3.14/180)/32.2)

Period:

=2*PI()*(((DISP^1.744/35.5)/(0.04*32.2*LWL*64*(0.82*BEAM)^3))^0.5)

~ ~ _/) ~ ~ MJH

[sandy stone]

Originally Posted by wingssail

Let me go further in what capabilities I appreciate in an ocean cruising boat:

1. Rugged construction of hull, keel rudder, rig and deck. It does not have to be overbuilt or a "brick **** house" but it should be solid.
2. Tightly sealable hatches including the main companionway to keep water out in rough conditions or rain.
3. Clear decks. Nothing on deck or strapped to the lifelines, so that when seas sweep over your boat they won't be tearing items loose, and that you can move about and work freely.
4. Avoid excessive weight aloft or in the ends of the vessel, no big arches for dingy and panels aft, only light weight in the bow or stern.
5. Excellent sailing performance, including windward ability. You should be able to sail in any direction in any conditions.
6. Simple sail handling layout, meaning direct sheet and halyard leads, good sized winches, low friction (few blocks on a line) and handy and clear places from which to operate the vessel.
7. Massive storage below for spares and tools, sails, and tankage, as well as provisions..
8. Easily handled by one or two people (preferably two, for safety) meaning things can be done quickly, efficiently, and simply.
9. Windvane, watermaker, good shower (with hot water)
10. Safe galley in a rough weather, and safe sea berths.
11. Good navigation station for use in rough weather

We sail a powerful 43' 1979 racing sloop which meets all of the above criteria.

Sounds pretty sensible. Oh, wait - I just noticed you have a 1979 boat - an IOR boat! You're surely going to die!

Getting a little more serious, I notice a few posters seem pretty fixated on calculated values for boats. Disp/length, OK, that I can see, although typical numbers have evolved over time. SA/disp is already getting a little questionable because typical numbers for masthead boats with overlapping jibs are not the same as for fractional boats with nonoverlapping jibs. BTW, displacement figures for production boats are often a fiction anyhow, so garbage in, garbage out.

Things like capsize screening ratios and motion comfort ratios are no more than somebody's pitiful attempt to quantify complex issues, that a Naval Architect might struggle to pin down, with simplistic calculations involving easily available numbers. They are at best meaningless, and more likely deceptive.
If a Contessa 33 is disqualified from "blue-water" status because of its capsize screening ratio, what does that tell you?