Pilothouse Variations -- Boreal

[stillbuilding]

This one:






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[Dockhead]

Originally Posted by stillbuilding

This one:

Attachment 125639

That actually looks pretty nice. Ticks a few boxes. Center cockpit plus pilothouse -- check. Very large walk-in engine room -- check. Dinghy garage -- big check. Bit of spring to the sheer -- that's nice. Plumb bow -- less so.

Doesn't show the underbody profile, but I guess it's a lifting torpedo keel like many others, plus flattish aft sections and not much forefoot. The torpedo keel might be a deal breaker; the others qualities might be marginally acceptable at that length.

Don't like the forward master cabin, but there will always be some compromise or another. Format of the pilothouse looks great, but might be hard to see over it from the cockpit. Rig looks pretty nice.

Thanks -- good tip. I'll write to them.

[Juho]

Originally Posted by Dockhead

Motor sailers are so much identified with Nauticats that I think another definition of a motor sailer would be any boat which resembles a Nauticat

That's true, but all this comes from the long Nauticat 33 - 44 tradition. Nauticat's pilothouse range and traditional motorsailer range are however very different. Both lines have pilothouses (entrance from the side vs. entrance from the cockpit), but otherwise those two categories look quite different (with some smaller commonalities, like solid GRP and teak rails).

Motoring optimized underbody is heavy D/L and has plenty of wetted surface -- that is a tradeoff intended to gain motion comfort but with a sacrifice of sailing performance.

Btw, if you plan to get a long and narrow boat, also that adds wetted surface. A short plump boat would be better from that point of view.

Added weight of heavy cruisers does not really contribute to their motoring capabilities. That's for sailing, stability and strength. A light boat would motor better. Traditional motor sailers are on the heavy side though, but not because of motoring. Maybe more for large interior space, and sailing and living comfort.

I note also that the largest Nauticat motor sailer model (441) is actually quite narrow (makes D/L smaller).

Look also at the aspect ratio of the keel -- this is very important. The Nauticat 515 has a very long fin keel. This is good for tracking and makes the boat sea-kindly, but it increases wetted surface

How do you count the wetted surface? One could make the keel shorter and deeper, but keep the same width. The wetted surface would be the same. Then one could drop part of the lead to the bottom of the keel, to make it a bulb, without changing the wetted surface much in either direction. If you continue and make the keel very short and add weight to the bulb (making it a light dagger with heavy bulb, as in racing boats) then you would save in wetted surface, but losing keel surface area would mean more drift.

A typical cruiser keel is not an efficient hydrofoil but just a regular keel. I'm not sure how the depth vs. length of a regular keel (with same wetted surface area) influences drag (is there some meaningful difference or not).

And another way to look at this is that, as I've written before, nearly all cruising sailboats these days are really used as motor sailers, making a large proportion of their miles using the motor or motor-sailing.

As we all know well, catamarans are the most obvious motor sailers from this point of view.

One reason for that is the difficulty in getting a loaded down cruising sailboat to go upwind, and another is that if your boat motors well, as nearly all cruising sailboats these days do, there really isn't any reason to bob around waiting for better wind, when you could just put on the engine and continue towards your destination.

Beating upwind is always much more inefficient than sailing close to upwind. Many cruisers switch to motoring at that point. Even in perfect wind conditions the alternatives are motoring forward at hull speed vs. zigzagging at hull speed.

So if you were to intentionally sacrifice some upwind ability and light wind ability, gain some seaworthiness and motion comfort, and make up for that with more engine power and tankage -- isn't that just a very logical tradeoff?

I'm not an expert on what makes a good upwind performer. But adding extra weight does not help, so a heavy cruiser might still keep only small amounts of fuel and have a small engine, to keep the weight (of stuff that is not related to sailing performance) down. Maybe better to invest in strength and stability as much as needed, and then concentrate on upwind efficiency.

When I think about this, Nauticat must have thought something along these lines, when they introduced their pilothouse line of sailboats. They certainly are not racer level upwind performers, but quite clearly a step in that direction (from the traditional motor sailer line).

So I like motor sailers in general and Nauticats in particular, even if they aren't exactly what I want for my particular style of cruising. But then I'm just an old boat slut who likes nearly all boats for one reason or another, so my liking them may not mean very much.

My preferences: good boat quality, good interior quality, good pilothouse. Since sailboats are about the slowest vehicles anyway, and I have no need for fast passages (you may have different preferences here), I'm satisfied with having decent speed and decent upwind capabilities. Also I am in love with all kind of boats, but some interests and use cases must come before others.

[Polux]

Originally Posted by Juho

Hull appendices? Southerly 49 seems to have a lifting keel and no skeg. Nauticat 515 has a fixed fin keel and skeg. Nauticat 385 has a fixed fin keel and skeg. Nauticat 385 has less rake in the bow than 515, maybe a slightly flatter body, but maybe those are not appendices. Are you talking about efficiency of cruising or efficiency of racing / max speed?

Not hull appendices, Hull and appendices, meaning shape of the hull, keel and rudder.

Yes as you pointed out the modern Nauticat is more similar in what regards hull shape with the Southerly than with the old designed Nauticat and that is to be expected due to design evolution.

No, not racing efficiency, sailing efficiency. After all all those are first sailing boats and then cruising boats...or maybe not

[Polux]

From Berkemeyer this is the one that I like most, along the lines of Adventure 55 but with a more interesting interior with a deck saloon an chart table with full view around.

Huge storage and huge garage for a really big dinghy.


But this seems more according to Dockhead wish list. Bigger boat, narrower, smaller garage, less storage, sailing with more heel but nice boat anyway with a better upwind performance.



Kees Van de Stadt has also some interesting designs that may fit the bill, or they can be modified to fit.

[Juho]

Originally Posted by Polux

Yes as you pointed out the modern Nauticat is more similar in what regards hull shape with the Southerly than with the old designed Nauticat and that is to be expected due to design evolution.

Not really, I think a skeg resembles a skeg, and a fixed keel resembles a fixed keel. Evolution will show us which random mutations will survive. The tested good old designs are likely to survive.

Modern times have introduced new materials, and they are likely to have some influence. GRP was a key new material few decades ago. After that, maybe light materials will add something to the equaltion. Water has not changed much, which means that good cruising solutions will not chance quickly. Racing rules on the other hand may change often, and introduce new ways to optimize performance there.

No, not racing efficiency, sailing efficiency. After all all those are first sailing boats and then cruising boats...or maybe not

Cruising includes often also living aboard, sleeping, carrying stuff, being safe etc.

[Matt Johnson]

Originally Posted by Dockhead

That actually looks pretty nice. Ticks a few boxes. Center cockpit plus pilothouse -- check. Very large walk-in engine room -- check. Dinghy garage -- big check. Bit of spring to the sheer -- that's nice. Plumb bow -- less so.

Doesn't show the underbody profile, but I guess it's a lifting torpedo keel like many others, plus flattish aft sections and not much forefoot. The torpedo keel might be a deal breaker; the others qualities might be marginally acceptable at that length.

Don't like the forward master cabin, but there will always be some compromise or another. Format of the pilothouse looks great, but might be hard to see over it from the cockpit. Rig looks pretty nice.

Thanks -- good tip. I'll write to them.

This is the one I pointed you to at least a year ago. Again, the benefit with this boat is dinghy garage orientation and that it can still have a single rudder vs twin rudders needed if you put the dinghy fore and aft.

By the way, if you'd like to talk to someone who has sailed most of these boats for Yacht.de, let me know and I'll put you in touch with him.

Matt

Sent from my LG-V410 using Cruisers Sailing Forum mobile app

[Juho]

Originally Posted by Juho

Btw, if you plan to get a long and narrow boat, also that adds wetted surface. A short plump boat would be better from that point of view.

I did some rethinking on this. As far as I have understood, you will buy speed by making the LWL long enough. But you don't need all the interior space and load carrying capability that the planned LWL might offer. In this case it makes sense to make the boat narrow, and reduce wetted surface that way. The boat will be also light (maybe some empty/light space at both ends), which will further reduce the wetted surface.

But you want to sail efficiently upwind and you need to fight against heeling. You could do this by adding weight to the keel. This will add wetted surface. Or you could add width to the boat (maybe diamond shape instead of delta shape). This would also add some wetted surface. I guess you need to take one of those onboard, probably some of both.

The outcome will be a big and fast diamond shaped canoe with some width to add stability . http://www.canoeing.com/canoes/choos...n-symmetry.gif

The keel should be a deep bulb keel, except that you probably want a strong fixed keel with low draught, so you need to make some compromises also there. Maybe even to the extent of getting a "motor sailer like" long fin keel with a bulb . http://www.cruisersforum.com/forums/...1&d=1465288642

Low masts were on the shopping list. That will reduce the tendency to heel (and need of ballast and width). Maybe a long enough hull could have even three masts (ugly?). Wind is also faster higher up, so maybe two slightly taller masts (with roached sails) would be a better option.

In short, I understand better now how a fast non planing boat can lose wetted surface by making the hull a bit narrower than usual.

[Dockhead]

Originally Posted by Juho

I did some rethinking on this. As far as I have understood, you will buy speed by making the LWL long enough. But you don't need all the interior space and load carrying capability that the planned LWL might offer. In this case it makes sense to make the boat narrow, and reduce wetted surface that way. The boat will be also light (maybe some empty/light space at both ends), which will further reduce the wetted surface.

But you want to sail efficiently upwind and you need to fight against heeling. You could do this by adding weight to the keel. This will add wetted surface. Or you could add width to the boat (maybe diamond shape instead of delta shape). This would also add some wetted surface. I guess you need to take one of those onboard, probably some of both.

The outcome will be a big and fast diamond shaped canoe with some width to add stability . http://www.canoeing.com/canoes/choos...n-symmetry.gif

The keel should be a deep bulb keel, except that you probably want a strong fixed keel with low draught, so you need to make some compromises also there. Maybe even to the extent of getting a "motor sailer like" long fin keel with a bulb . http://www.cruisersforum.com/forums/...1&d=1465288642

Low masts were on the shopping list. That will reduce the tendency to heel (and need of ballast and width). Maybe a long enough hull could have even three masts (ugly?). Wind is also faster higher up, so maybe two slightly taller masts (with roached sails) would be a better option.

In short, I understand better now how a fast non planing boat can lose wetted surface by making the hull a bit narrower than usual.

Generally all true, but hull form is more complicated than that.

You correctly said before that a long narrow hull will have more wetted surface per unit of buoyancy. So with such a hull you trade some wetted surface for a better "fineness ratio".

"Fineness" is length versus beam, and a finer hull is easier to drive through the water. Fineness in fact is why catamarans are able to exceed hull speed fairly easily.

Narrow boats have less FORM STABILITY, but narrowness or fineness does not affect BALLAST STABILITY, so you can make a narrow boat with just as much righting moment as a wide one if you're willing to put in more ballast, or give it a deeper keel. Of course more ballast makes the boat heavier, which is bad. But the more easily driven hull requires less sail power, so you can make the rig lower. One advantage of more ballast stability is that this works even when the boat is knocked down, so this is safer than boats relying greatly on form stability.

That's how Dashew made the Sundeer such a fast boat despite modest sail area, modest height rig, etc. That's a fantastic formula for a short handed long distance cruising boat.

A split rig can improve this even more, but a split rig brings other disadvantages, especially windage which really hurts ketches upwind. But this disadvantage might be partially offset by less ballast required, and may also be partially offset by getting the masts far away from each other. Dashew's ketch rigged Sundeer is a really excellent sailing boat -- succeeded with exactly these measures.

I like ketches like Dashew's and would be seriously tempted by all the advantages of flexibility of sail plan, etc., but I don't think my new boat will be quite big enough for this to be the optimum solution, especially since I am not a trade winds sailor and so really must have really good upwind ability. So it will be a cutter rig.


As to the keel -- a "motor-sailer-like long fin keel" is the wrong solution for a boat where sailing performance is desired. Hydrodynamic performance of the keel is related to aspect ratio, so should be as long and thin as is consistent with strength and tracking. A torpedo bulb work best, but is unacceptable on a long distance cruising boat because of the propensity to catch nets, lines, anchor chain, etc. So of course compromises must be made (like everywhere), and the right compromise for this purpose is probably a moderate aspect ratio bulb keel like you find on most high end cruising boats. NOT long! But not rapier-thin, either.

Dashew's boats had in mind trade winds sailing and shallow tropical waters encountered by typical circumnavigators, so his compromises are somewhat different from mine. I could tolerate a bit more draft -- I think up to maybe 2.70. That's a reasonable draft for a reasonably high performance narrow 62 foot boat, not great, but not that bad, and not too deep to cause big problems.

Raising keels or centerboards is another way to do it, but I am skeptical so far about (a) reliability; and (b) hydrodynamic effectiveness of the various designs. I will have to keep studying this before I can form an opinion.

[Juho]

Originally Posted by Dockhead

Generally all true, but hull form is more complicated than that.

You correctly said before that a long narrow hull will have more wetted surface per unit of buoyancy. So with such a hull you trade some wetted surface for a better "fineness ratio".

"Fineness" is length versus beam, and a finer hull is easier to drive through the water. Fineness in fact is why catamarans are able to exceed hull speed fairly easily.

Maybe one could say that narrow boats make a smaller bow wave, and therefore climbing on top of the hull length (hull speed determining) wave is easy.

Narrow boats have less FORM STABILITY, but narrowness or fineness does not affect BALLAST STABILITY, so you can make a narrow boat with just as much righting moment as a wide one if you're willing to put in more ballast, or give it a deeper keel. Of course more ballast makes the boat heavier, which is bad. But the more easily driven hull requires less sail power, so you can make the rig lower. One advantage of more ballast stability is that this works even when the boat is knocked down, so this is safer than boats relying greatly on form stability.

Yes, a cruiser should bounce quickly back after being slammed 90° to the water.

That's how Dashew made the Sundeer such a fast boat despite modest sail area, modest height rig, etc. That's a fantastic formula for a short handed long distance cruising boat.

A split rig can improve this even more, but a split rig brings other disadvantages, especially windage which really hurts ketches upwind. But this disadvantage might be partially offset by less ballast required, and may also be partially offset by getting the masts far away from each other. Dashew's ketch rigged Sundeer is a really excellent sailing boat -- succeeded with exactly these measures.

Maybe modern carbon fibre masts can help a bit here, at least with the weight, not sure if they can be built narrower than aluminium masts.

I like ketches like Dashew's and would be seriously tempted by all the advantages of flexibility of sail plan, etc., but I don't think my new boat will be quite big enough for this to be the optimum solution, especially since I am not a trade winds sailor and so really must have really good upwind ability. So it will be a cutter rig.

Yes, trade wind optimization is different than overall and/or upwind optimization.

As to the keel -- a "motor-sailer-like long fin keel" is the wrong solution for a boat where sailing performance is desired. Hydrodynamic performance of the keel is related to aspect ratio, so should be as long and thin as is consistent with strength and tracking. A torpedo bulb work best, but is unacceptable on a long distance cruising boat because of the propensity to catch nets, lines, anchor chain, etc. So of course compromises must be made (like everywhere), and the right compromise for this purpose is probably a moderate aspect ratio bulb keel like you find on most high end cruising boats. NOT long! But not rapier-thin, either.

I lost the picture in my previous mail, so I attach it below. You could see that form as a strengthened torpedo keel with no protruding torpedo/ballast head. It is raked to get quickly rid of any possible nets, whales etc. Maybe you would get a slightly deeper and narrower keel (keeping the same surface area), but with the same overall design, no doubt, unless you get a strictly vertical (dagger) raising keel or a tilting keel.

Dashew's boats had in mind trade winds sailing and shallow tropical waters encountered by typical circumnavigators, so his compromises are somewhat different from mine. I could tolerate a bit more draft -- I think up to maybe 2.70. That's a reasonable draft for a reasonably high performance narrow 62 foot boat, not great, but not that bad, and not too deep to cause big problems.

A big boat will have a big tender that will take you safely to the shore. A big boat can also accept windier anchorages. Maybe all you need to care is to get in to your favourite marinas. Based on this you could go also deeper than 2.70.

Raising keels or centerboards is another way to do it, but I am skeptical so far about (a) reliability; and (b) hydrodynamic effectiveness of the various designs. I will have to keep studying this before I can form an opinion.

I guess raised keels are often torpedo keels. If they are wider, also the keel box inside the boat becomes bigger and heavier. A keel that folds backwards could be lighter. A canting keel would help also your upwind performance.

I wonder if there are any boats that would have both a backwards folding keel and a backwards folding rudder. That would be very forgiving when hitting whatever underwater objects. Could allow even beaching, and whatever shallow waters.

[TeddyDiver]

Originally Posted by Dockhead

A split rig can improve this even more, but a split rig brings other disadvantages, especially windage which really hurts ketches upwind. But this disadvantage might be partially offset by less ballast required, and may also be partially offset by getting the masts far away from each other. Dashew's ketch rigged Sundeer is a really excellent sailing boat -- succeeded with exactly these measures.

I like ketches like Dashew's and would be seriously tempted by all the advantages of flexibility of sail plan, etc., but I don't think my new boat will be quite big enough for this to be the optimum solution, especially since I am not a trade winds sailor and so really must have really good upwind ability. So it will be a cutter rig.

One consideration having a single stick on slender boat is the length of the boom. Surely lesser issue with a cutter but depends how slender the hull and length of the boom. One of the things I'd like to avoid is slamming the boom to sea..

BR Teddy

[barnakiel]

Had a look at adventure 55 via the YM.

Very odd combo of features. Flat wide fore. Reminds me of early Benes.

Otherwise quite a piece of alloy hull. Nice base for one's own mods.

b.

[Dockhead]

Originally Posted by TeddyDiver

One consideration having a single stick on slender boat is the length of the boom. Surely lesser issue with a cutter but depends how slender the hull and length of the boom. One of the things I'd like to avoid is slamming the boom to sea..

BR Teddy

Very good point, and something to keep in mind.

But this will be less of a problem with a lower, high aspect rig.

In rough weather downwind I get rid of the mainsail and center the boom, for this reason, and also to move CE forward to reduce any tendencies to broach.

Sent from my D6633 using Cruisers Sailing Forum mobile app

[TeddyDiver]

Along these resent topics, in this thread, single handed monohull and a couple of others, I've been mind gaming what my perfect cruiser would be like. Just for fun and with a presumption of a win in lottery which by the way is impossible becouse I don't do lotto. Anyway, made a sketch of the thoughts while watching my baby girl to take her day naps.

But here it is (sorry about the mix of metric/imperical, one square equals 1m)
LOA 66ft, LWL 59ft, Beam 16.5ft, Draft min 6.6ft, Disp 46 metric tons. Ketch rigged two sails on both sticks, SA~150sqm. Two daggerboards back from the screw and swing keel in and out from the longkeel. 6 cylinder diesel with CPP propeller.
From the stern: dinghy bay and storage. On port pantry and galley, stb head, sauna and dinette (with room for guests). Above the center cockpit and infront of it a pilothouse. Below the engine room. The bedroom, a head on stb. Workshop 'til the collision bulkhead.

[neilpride]

Looks nice but I think 150 sqm of sail area and 46 tons are in disagreement unless its a heavy motorsailer...