Semi-displacement and Full Displacement Hulls

In the OP initial post, he mentioned that, in the past there have been as many as 6 on board. If this is still the case, you may want to consider a larger boat. Also, you left out what you have budgeted for such a purchase, unfortunately, that is a VERY important consideration.

With such a large investment, you also want to consider the resale value and desire. In this arena, I have found that high(er) quality, full displacement vessels have done much better than any of the SD style vessels.

If it were me, I would keep an open mind and look at as many vessels as possible. Some on my own list are: Selene, Nordhavn, Cherubini, Krogen, Fleming, as well as some of the later DeFevers. Of course there are others out there but these are proven designs with great histories.

For the "Big U" you will have to consider being away from land for a fairly extended period of time, and when on the Land along the way, it may not offer the most modern of facilities for provisioning.

You will need a fair amount of space for provisions, minimum 600 GPD water maker, tankage, both water and fuel. Fuel Scrubber System, spare parts, etc.

If single engine, I would consider rigging the generator as a limp home engine.

If you feel that a Grand Banks will do the job for you, it opens up a few more boats that will do the job as well, or better than the GB's. Too many to consider in this category to attempt to list.

What ever you decide, HAVE FUN!

Capt.Bill11 said:

I'm not sure if agree with that. The majority of stabilized non-commercial boats are hard chine I'd say. And the stabilizers work just fine.

And considering the way a full displacement boat would behave roll wise in a beam sea you could say it would cause the stabilizers to work harder to dampen its rolls.

Where as a hard chined boat is stiffer and resist roll so the stabilizers may not work as hard at least initially.

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Exactly Bill. You will be hard pressed to find, say, a non stabilized classic Hatteras motor yacht. They exist, but rare. Mine benefitted greatly from the stabs and the Naiads never seemed particularly stressed, partly because the initial stability is very good on these boats and doesn't require anything from the stabs, while FD is going to roll, gently, right away. Just watch the little needles on the Naiad display on each kind of boat in similar seas.

Even though there are small islands of somewhat useful information on this thread, in my opinion the OP would be better off just ignoring the whole thing. Pick up a copy of Gerr's "The Nature of Boats" for starters.

GBs are great boats by the way, and will take green water on the pilot house windows all day long, I can testify.

While GBs may not be everyone's first choice for a bluewater cruiser, they do get around.

Hair of the Dog | Yachting Magazine

http://www.grandbanks.com/images/discovery/experience/spray/backissues/spray/v11n1.pdf

bayview said:

Good advice Kevin though most wont believe you.

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Nope it's easier to dream of the boat you cannot buy because that gives you an excuse for not going.

For those that can afford them and actually cruise them the FD passagemakers make nice platforms for exploring.

For the rest of us the scenery is much nicer sitting on the boats we can afford to buy and actually cruise than it is sitting in our offices while saving for or paying for a dream boat.

Carleton Mitchell hit the Eastern Caribbean in a GB 42 back in the 60's called Sans Terre. He was a former winner of the Newport-Bermuda race with his sailboat Finnisterre. He had sailed the whole Caribbean chain in the 40's with a boat called Carib and then in Finisterre years later, documenting his voyages in National Geographic Magazine. I blame these articles for giving me the desire to spend my life afloat upon these waters. He sure had plenty of experience with the challenges and realities of cruising off shore. The sad truth is that in typical Caribbean Trade Wind passages the boat is going to be moving around quite a bit regardless of hull form or size. And while the chart looks like short "Island Hopping" is the order of the day in practice when the wind and seas funnel through the passages things get pretty lively. For me the order of importance is 1. STRONG 2. RELIABLE PROPULSION 3. RELIABLE PROPULSION WHEN THE OTHER ONE FAILS. 4. A CREW THAT IS READY FOR THE DISCOMFORT.

We looked at a Nordhaven 40 before buying our Nova Sundeck. If we were going out in the Bering Sea I would pick the Nordhaven, but for southern California waters, the Nova is just fine, and a whole lot cheaper.

ksanders said:

To answer your question, passagemakers are almost all FD boats because of two reasons.

1. A FD boat has better fuel economy, and in general can carry the fuel necessary for crossing oceans.

2. A FD boat can in general withstand seas of a larger magnitude than a SD boat. This is necessary for passagemaking because our current technology only allows for an approx 72 hour firm weather forecast duration. Therefore a passagemaker must be able to operate in whatever sea state might happen.

We all need to remember and take note that cruising anywhere along a coastline, or between islands is not passagemaking. It does not require the fuel range or the seaworthiness that crossing open oceans requires. Therefore it does not require a FD boat, or a boat capable of crossing oceans.

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I suspect there's a third (at least) reason, having to do with personal inclination and a wallet to back it up. Many who have the inclination for transoceanic passages and who actually intend to follow through with that aspiration... also have the money to buy a good tool for the job.

Others maybe just fall into deeper water during their "use what you've got" phase.

Good point that "cruising" doesn't necessarily require passagemaking in the transoceanic sense.

-Chris

Capt.Bill11 said:

I'm not sure if agree with that. The majority of stabilized non-commercial boats are hard chine I'd say. And the stabilizers work just fine.

And considering the way a full displacement boat would behave roll wise in a beam sea you could say it would cause the stabilizers to work harder to dampen its rolls.

Where as a hard chined boat is stiffer and resist roll so the stabilizers may not work as hard at least initially.

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Capt.Bill11 and Caltex,
In waves when more water comes up under one side of a boat the extra lift on that side causes the boat to roll. The round bottomed boat I showed pics of will experience much less upward force on the wave side whereas the GB or Hat will strongly lift "right now" producing a snap roll that's very uncomfortable. The narrower and rounded FD hull will have much less force lifting causing the roll. BUT there is much less force counteracting the lift from the other side so the response can be slow and not much force to stop the roll so lots of slow rolling results. So a FD boat will roll deeper (more degrees) and if the wrong timing of wave encounters are present heavy rolling can result. But on a FD stabilized boat very small forces are needed to keep her from rolling or rolling too much.

And if a wide hard chine boat has stabilizers and they "work fine" I'm going to assume they're going to be big and powerful stabilizers.

manyboats said:

R

anger42c wrote
"I wonder if there's really that huge a difference between a stabilized full-displacement hull and a stabilized semi-displacement hull. Measurable? If so, how much delta is due to hull form, and how much due to the stabilization system?

If the system (active fin) is part of the design and called for a NA the system would be much more effective and/or smaller on the FD boat. Much less stabilization will take place on a low deadrise hard chine boat for a given size system. So yes to your question is there is a very noticeable difference and the difference will vary a lot because the differences in hulls and what people think a FD hull is. Our archives will show that is not clear.

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Maybe the amount of difference also varies a lot because of the differences in various owners' perception of roll, too. (Much like the local dock neighbors who sometimes come back in 5' seas... when the nearest buoy reports 2'.)

In any case, a shopper's possible follow-on question might also be "how much more is it worth" to choose one hull form over another. Let's say FD is 30% better, roll wise. (Just an example. 10% 20% whatever) Then how much more does a decent FD boat cost compared to an equally decent SD boat? 30% more? Less than 30%?

How often might that example 30% come into play? On one trip? A few times per year? Every trip? In any case, is the delta worth it?

IOW, how can a shopper measure (or at least get a feel for) the amount of difference he/she might find useful, and how much that difference is worth in $$.

Just thinking out loud, as it were...

-Chris

Keep an open mind when searching for the right boat for the task required. ...and look at what the local fisherman use. As has been said many times - all boats are a compromise.

I had no intention on buying a motorsailer, but it turned out to be the best boat available in my price range for handling the rough local conditions. Any boats with active stabilizers were out of my league. Paravanes are hard to find on smaller boats.

In the end - it got me on the water at a price I could afford, and I'm gaining more experience at how to deal with the weather, waves and other challenges. I'm happy!

sgkramer said:

Hello all,

I just joined the forum and this is my first post. I am not trying to start a fast boat/slow boat debate here...

Thanks for your time,
Sam

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Don't worry Sam, it doesn't take much to get these guys going. Come on back and let us know if we are providing the kind of feedback you need.

CPseudonym said:

Don't worry Sam, it doesn't take much to get these guys going. Come on back and let us know if we are providing the kind of feedback you need.

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Actually the debate is exactly what he needs to. There is not a simple, right answer. People don't agree on this subject. So he gets all views and then he can decide who to believe or really who he is more like. It's obvious if you just look that boaters are passionate about very different boats than each other.

manyboats said:

Capt.Bill11 and Caltex,
In waves when more water comes up under one side of a boat the extra lift on that side causes the boat to roll. The round bottomed boat I showed pics of will experience much less upward force on the wave side whereas the GB or Hat will strongly lift "right now" producing a snap roll that's very uncomfortable. The narrower and rounded FD hull will have much less force lifting causing the roll. BUT there is much less force counteracting the lift from the other side so the response can be slow and not much force to stop the roll so lots of slow rolling results. So a FD boat will roll deeper (more degrees) and if the wrong timing of wave encounters are present heavy rolling can result. But on a FD stabilized boat very small forces are needed to keep her from rolling or rolling too much.

And if a wide hard chine boat has stabilizers and they "work fine" I'm going to assume they're going to be big and powerful stabilizers.

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In many ways it boils down to which type of roll a person can deal with in the long run. Some people prefer one style of rolling over the other. And a low hard chine boat can be more stabile at anchor. One of my favorite boats at anchor are the Marlows. Low, fairly wide, hard chined and very comfortable at anchor.

Stabilizers do work just fine on both types of hulls and are relatively large and definitely powerful in both cases. The have to be to work efficiently and over come the forces in play.

Passage making in a boat sounds like torture to me, bouncing/rolling around for weeks at a time. Ships, on the other hand, were made for passage making.

:


Without active roll stabilization of any type, the most steady hull for a power boat in rough water would probably be a deep vee planing hull such as a Bertram 35. (until you run out of fuel)

AusCan said:

:


Without active roll stabilization of any type, the most steady hull for a power boat in rough water would probably be a deep vee planing hull such as a Bertram 35. (until you run out of fuel)

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Or until you have to slow down because of sea state then beam seas woud have some of the saltiest puking...

Have seen it plenty of times.

Like Mark posted...any boat at some sea state is just beyond it's desired capabilities...even ships...but the bigger she is the more rare the times the sea wins.

Once while bouncing around entering San Francisco in on my passage capable sailboat I realized how I really wanted to cross oceans when I looked up and saw planes bound for SFO

I look at some form of stabilization, whether stabilizers or paravanes as a necessity. Now I know it's not on the level of food and water but it adds so much to the enjoyment. Once one has them, they never want to go back. Most characteristics and options of boats I see as very dependent on your intended use, but stabilization isn't one of those things. Every use of a boat involves some need. Although the boats I had on a lake were too small for it, I can see many times even on lakes and rivers it would have been nice, when all the weekend boaters were throwing wakes everywhere.

Stabilization may not be as important as food or water, but for those of us guys who are married/attached it may be the difference between cruising and not cruising. Depends on the boat and the cruising area.

Bay Pelican said:

Stabilization may not be as important as food or water, but for those of us guys who are married/attached it may be the difference between cruising and not cruising. Depends on the boat and the cruising area.

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It's called "Pleasure Boating" so I'm for everything that makes it more pleasurable. We are fine with conditions many here wouldn't want to be in but at the same time we do try to make things as comfortable as possible. Safety is paramount, but pleasure is then what we all want in addition to it.

Guys w stabilizers probably don't ride Harleys cause they vibrate.

manyboats said:

Guys w stabilizers probably don't ride Harleys cause they vibrate.

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I don't ride Harleys for many reasons and vibration is the least of them.

but

Probably a better analogy though would be "don't ride Harley's over mountain trails and through the woods" as last I knew most road Harley's on smooth surfaces and the water is often not smooth. What if while you were stopped at the light on a Harley the road started tilting back and forth side to side about 20 degrees?

while this conversation has morphed to stabilization,the one difference that I have noticed on a full displacement vs. semi is storage.Most fd boats have considerable more storage than semi,due to the hull design,as well as being able to hold much more weight with little compromise to draft.albeit,all additional weight on either should be stored as low as possible to not affect stability.So in my humble opinion,fd boats are more suited for longer distance cruises,or more time away from the marinas.

tinped said:

while this conversation has morphed to stabilization,the one difference that I have noticed on a full displacement vs. semi is storage.Most fd boats have considerable more storage than semi,due to the hull design,as well as being able to hold much more weight with little compromise to draft.albeit,all additional weight on either should be stored as low as possible to not affect stability.So in my humble opinion,fd boats are more suited for longer distance cruises,or more time away from the marinas.

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At a certain size and purpose...that "storage and carrying" capacity becomes irrelevant to most recreational boats.

Sure a coal barge needs to be full displacement...but a lot of mega yachts that aren't expedition yachts are not FD.

Even in sizes down to 50-60 something feet a boat can be a passagemaker and not be FD without sacrificing too much for speed, accommodations and amenities. Sure the design and materials become more out of the ordinary...but they don't fit the "must be displacement" rule.

psneeld said:

At a certain size and purpose...that "storage and carrying" capacity becomes irrelevant to most recreational boats.

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Perhaps we have two discussions, one for the majority of pleasure boat which are under 65 feet and the other for those boats which are over 65 feet. The over 65 feet long boats fall into a different category for many reasons in addition to the need or lack of need for stabilization or hull form.

Bay Pelican said:

Perhaps we have two discussions, one for the majority of pleasure boat which are under 65 feet and the other for those boats which are over 65 feet. The over 65 feet long boats fall into a different category for many reasons in addition to the need or lack of need for stabilization or hull form.

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Exactly like other SD/FD discussions...there is no "hard" line to draw through...so it becomes a constant changing of parameters to even discuss.

Sure I'll agree that the more "standard" boat designs under 65 feet tend toward FD to be reasonable passagemakers and a good point about they really need to be stabilized...

My point is that an "unconditional" statement about all or mostly all passagemakers is just not true or completely relevant. As Mark pointed out...size usually drives passagemaker design where smaller passagemakers are forced to fiddle with design parameters to accomplish as many design desires as possible...if speed is one...the FD is out and other ways are figured in to accommodate engine size and fuel consumption.

I know I'm talking about a small time vessel what can I expect with my 36 FD 1976 Gulfstar Mark II in moderate to light seas?
Thanks in advance...
Bill

I would stay away from the Zeus drives if you're just in shoaling waters at all. I also love my stabilizers and I consider them a priority.
Over the past year of cruising full time we have used our fly bridge less than 1/2 dozen times, the pilothouse as others have mentioned is awesome and with a centrally positioned helm you have great access to anything you need.

I ditto the comment about chartering what you are looking at if time was on my side and we were looking at another boat which we are not I would definitely charter.

Lastly no boat will give you everything you need unless you just won the lottery....

Happy hunting

Takes Two
Currently in Tonawanda NY

gwkiwi said:

I would stay away from the Zeus drives if you're just in shoaling waters at all. I also love my stabilizers and I consider them a priority.
Over the past year of cruising full time we have used our fly bridge less than 1/2 dozen times, the pilothouse as others have mentioned is awesome and with a centrally positioned helm you have great access to anything you need.

I ditto the comment about chartering what you are looking at if time was on my side and we were looking at another boat which we are not I would definitely charter.

Lastly no boat will give you everything you need unless you just won the lottery....

Happy hunting

Takes Two
Currently in Tonawanda NY

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If I could easily do it I would remove the upper helm on my Gulfstar. I may end up doing it once I get the boat back to my home marina in NJ. To me it's wasted space I could use for additional solar panels and antennas. It's one less set of gauges, throttle and engine cables and steering controls to deal with. It would also lower my overall height possibly lowering my CG. I see practically no reason to use the upper helm given the view and comforts I will have at the lower helm.
Bill

gwkiwi said:

Over the past year of cruising full time we have used our fly bridge less than 1/2 dozen times, the pilothouse as others have mentioned is awesome and with a centrally positioned helm you have great access to anything you need.

I ditto the comment about chartering what you are looking at if time was on my side and we were looking at another boat which we are not I would definitely charter.

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Just shows how different we all are. In terms of use of fly bridge, if by use you mean been on it at all, we use ours at least 70% of the days we cruise. If by use, you mean use the flybridge helm, we use it probably 40% of the days we move. Now I don't mean 40% of the time as sometimes that may just be a few hours out of the day.

Now we live in South Florida, so generally great weather for bridge. But the funny thing is cruising in the PNW we find ourselves moving up when we get a nice day, generally anything above 65 degrees and not raining, just to enjoy the day of nice weather.