How do you feel about plumb bows on cruisers?

[rslifkin]

Originally Posted by ohthetrees

In big seas, and strong winds, if I didn’t slow the boat, I’d be planing, and going god know how fast down the waves. 20kn? I’d be terrified of tripping over the fin keel. Some people do advocate for the “go fast” approach, but I think it would take an expert helms-person using their full attention to carry it off. That is tough on a 2 week passage. I prefer to keep it in the realm the autopilot can handle.

The fin keel brings lots of performance advantages, and again has more pros than cons. But a con is that the boat wants to turn, which is only held in check by a large powerful rudder (my rudder blade is 8’). When going fast down waves, I can feel the boat wanting to turn, and so far, I’ve kept it at speeds the rudder can cope. I feel it is increasingly likely the faster I go that I turn uncontrollably and trip on the keel in big following seas. I want to avoid that. So far keeping it <9kn has kept it manageable and comfortable. There is some safety margin there, I could probably go faster safely, but I’m a cruiser, not a racer, I’ve got kids aboard, bla bla bla.

You definitely need a good hand on the wheel or a good autopilot. But if the rudder is designed well and has good waterflow, rudder authority should increase as speed increases. So as long as small corrections can be made accurately, the rudder should have plenty of power to keep the boat in line. I can definitely see how a broach would get very ugly with a hull that naturally wants to lean outwards in a turn and has a big keel down there, however.



Someone would have to confirm this, but I'd also think that running with more headsail and less or no main would be more stable in a high speed surfing scenario, as the pull on the boat is further forward (and should do a better job of keeping you from swapping ends). Plus, it would give you more lee helm when not DDW, so if you start to get a bit sideways, the sails will want to turn you back downwind.

[dannc]

Originally Posted by Clivevon

Surprised no-one has mentioned Bristol Channel pilot cutters with their plumb bows:
https://cdnx.theyachtmarket.com/boat...8915085_wm.jpg
Sailed by 2 crew to take the pilot out to incoming ships - in all winds & weather & the fastest boat got their pilot the job. Real working boats.

Yep.

Tom Cunliffe has some YouTube videos about pilot cutters, here is one that leads to another.

https://www.youtube.com/watch?v=Tm5n5kNfhtA

Cunliffe owned one for quite some time and sailed her around Europe and across the Atlantic. If I remember right, the pilot cutter he owned is still out sailing and is well over a century old. I might be mixing up boats but I think it was built in France around 1900, to be used by pilots, but that business died and the boat was sold to be used as a private yacht.

Given the age and evolution of those boats they had to be seaworthy, sea kindly as well as easy to sail. Supposedly, the pilot boats went to see with only 2-3 people on board, the pilot and one or two other people to return the pilot boat to port. One of the people on board would be a boy.

The faster the boat, the farther out to sea she could go, AND stay, was going to get the ship. Pilots could be very wealthy. I don't know if it was one of Cunliffe's videos are something else I watched but they showed the very nice houses, that were very large, even by today's standards.

Kinda funny looking at old boat designs, old meaning at least 100 years old, how some designs, or design elements, are considered "new."

Later,
Dan

[Carlwasher]

Just a little Segway if I may...

What anchor fits best on the pointy end of a plumb bow??

It looks to me the Rocna Vulcan is a pretty good candidate.

[rslifkin]

The Vulcan would be a good fit for that. Mantus M1 would be up there as well. From when I did my last anchor search, those 2 had some of the shortest roller to tip distances when fully stowed (not sure how various designs would do clearance-wise during retrieval though).

[thomm225]

Originally Posted by Training Wheels

Glad to hear you determined that plumb bows aren’t good on 14’ power skiffs.

Thanks.

That was part of it but it was mainly by comparing plumb bows to rocker style bows going out Pensacola Pass during a seabuoy race in 1997 as I stated earlier.

I was on my plumb bow Nacra 6.0 but observing a Hobie 16 easily handling the 6'- 8' waves in the pass.

The inlet we used to come through coming in from the Atlantic with our 14' power boats back around 1971 as teenagers was another experience where I wouldn't have wanted a plumb bow.

Much easier to ride the back of a wave with the old style bow....and that's how we came thru that inlet. pick a wave a go with it....

https://www.youtube.com/watch?v=0ESuzVQ02D8

[Gerrycooper56]

Originally Posted by Cheechako

Huh? I guess this post in NOT about plumb bows.... but modern boats.
A long waterline/ plumb bow should pitch less than a traditional shape, right?

I could see a plumb bow being wet, if you watch real fast ocean racers, a lot of streaming spray comes from the bow.

If you think of a boat's length as it's waterline rather than overall: The overhang is weight which can cause some hobbyhorsing, but it also provides more bouyancy when the bow plunges into the water. I've often wondered how that works out in reality...

Seems maybe a near plumb bow with a bulge like Jimmy Durante's nose would be the best of all worlds... :>)

Well, having recently sailed from Curaçao to Cartagena on our Tayana 52 in winds up to 40 knots and seas over 10’ I wouldn’t believe that while surfing down waves I could go up to the bow to reposition the boom preventer and return to the cockpit dry(ish). I believe the overhang and flare kept the bow up.

[Happ]

Originally Posted by Jim Cate

This has been my experience, and quite dramatically so. One does need to keep excess weight out of the extreme bow area, but that is true of all designs to some degree. The bow on our boat isn't quite plumb, but the overhang is less than a foot, and our LWL is only about a foot less than LOA, and our beam isn't as exaggerated as some newer designs, but it sure ain't a CCA or even IOR shape! And the boat is way drier than my previous boats of those eras.

As to the relative "wetness" of such designs... perhaps the increased spray is due to pointing higher and going faster than in older designs, hmmm? Those factors surely promote spray reaching the cockpit area more than the shape of the bow!

Jim

Much of the spray comes from the flat underside of the hull. When the bow comes down the forward part slaps the the water like an open hand. The after goes out away from the hull so the wind can catch it and throw it at the cockpit. The flat bottom also has less wetted surface meaning less drag. The plumb bow allows for a longer LWL. That allows for a faster hull prior to surfing. All this allows for a larger interior with one caveat. They don’t have deep bilges which allow for great storage at or below the waterline.

the older designs with v-bottoms push water to the side as it plows back into a wave. They have a much gentler motion. Less violent

The modern designs are faster no doubt. The older designs are more seakindly and less violent motion. I’ve raced on some very fast offshore boats. they are not not very comfortable. If I’m going cruising in any ind of wind over 20 kn I’ll take and old long keel any day!

[raahell]

Originally Posted by Jim Cate

And in the case of a long overhang with the chain locker well forward, I suspect that this configuration emphasizes the effect of bow loading and leads to increased pitching/hobby horsing as a result.

Above is all conjecture, with no NA science to back it up.

I know I'm going to ruffle a few feathers here, but I'm going to relate some science to refute the above understanding which BTW is a commonly held belief i.e. having lots of weight at the boat's extremes leads to access movement around the lateral axis (pitching). According to science and naval architects I've worked with, the reverse is true. This is due to what's called "moment of inertia". To best understand this, visualize the tightrope walker with that long pole s/he uses to stabilize him/herself. That pole has heavy weights at its ends. These weights multiplied by the distance from the walker's point of rotation provides the moment of inertia. Now, according to one of Newton's laws (I forget the number), a mass resists any changes to its speed or direction. Therefore, those weighted ends will want to stay where they are and help the walker stabilize him/herself on the swaying tightrope. Same applies to a sailboat. If one were to concentrate all of a sailboat's mass to its central area (very low moment of inertia), the boat would pitch and roll much more pronounced that the same boat with some of it's more massive components pushed out at the bow and stern (high moment of inertia).

Nevertheless, sailors claim that their anchors and chains up in the bow leads to increased pitching. And some sailboat designers claim to reduce pitching/healing by designing anchor lockers near the midship and down low in the hull, vs high and in the bow. So why the discrepancy between science and observation? Perhaps this is because sailboat design is never about one or two scientific principles applied in clean, predictable circumstances. 200' of rode in the bow is also up high, which raises the boats center of gravity, which leads to increased instability. That's probably just the start of a more fulsome explanation...

According to science, that 200' of heavy chain should ideally be located at the bow but down as low as possible, this will give high moment of inertia AND lower centre of gravity, leading to reduced pitching, rolling and generally better seakindliness. A bulbous plum bow (like we're beginning to see on IMOCAs and some racing dinghies) would seem to offer that opportunity much more so than the traditional sailboat overhanging bow. But the design bureaus keep the rode up high and use the volume instead to create a huge V-berth with king bed. So it all comes down to science AND marketing in their eternal tug-of-war over sailors' hearts and minds. Conclusion: it's easier to sell a big V-berth than better seakindliness!

[rslifkin]

More weight in the ends will make it harder to start a pitching motion, but there's also more momentum behind any pitching motion. So if the hull shape doesn't damp out pitching well and the boat pitching gets synced up with the waves, you can start to build a rather significant amount of pitching when there's lots of weight in the bow to keep it going.

[wingssail]

[QUOTE=raahell;3375908..according to one of Newton's laws (I forget the number), a mass resists any changes to its speed or direction. Therefore, those weighted ends will want to stay where they are and help the walker stabilize him/herself on the swaying tightrope. Same applies to a sailboat... [/QUOTE]

The problem with this theory is that there are waves in the sea and no matter how much weight you concentrate in the bow those waves will cause the bow to rise. Then it will fall as the wave passes and all that inertia in the bow will cause it to plunge farther into the next trough.

Weight in the ends, particularly in the bow, does result in bigger motions and the plunging bow slows the boat. Lighter bows have faster up and down motions but show less dramatic vertical motion and less slowing affect of the hobby horsing.

Personally I prefer the boat which maintains a good speed and less dramtic motion when faced with waves.

[skenn_ie]

Plumb bows do what they are designed to go, go through waves rather than over them, and with minimal loss of speed. That is great until the swell exceeds the freeboard. They still go through the waves, but like a semi-submersible.

[Na Mara]

I saw this thread and just had to pitch in as I had one of those plumb-bowed, light displacement, bulb-keeled, broad-transomed sailboats with self-tacking jib and full-battened main (Hanse 370e) and I sold her and I bought a conservative, medium displacement yacht with overhanging bow, veed fore-sections, longish fin keel, half-skeg rudder, conservative rig with overlapping genoa.

The overwhelming reason for that change was seakeeping ability.

The hanse was great in many ways. With the wind anywhere abaft the beam she was a rocket (I had her up into the teens multiple times). She had a big cockpit and her interior was possibly more spacious than that of the Regina 43 that I replaced her with despite her being fully 6 ft shorter. She was a great family boat where everyone could easily work the sails (with the exception of reefing the mainsail which no matter what I did was really heavy work) from the safety of the cockpit.

However, that self tacking jib was impossible to set well off the wind or on the wind passed its second reef and that plumb bow was indeed very wet. This second point is not such a problem normally as you just don't go to the bow in those conditions but occasionally you have to. I remember one occasion in particular when we were running before a force 7 in the north sea and the shackle on the tack of the jib broke. I had to go up there and tie the tack of the jib down. I remember sitting there on that foredeck lashing away between submersions. It took 90 minutes because of the intermittent green water over the deck. Not fun!! And then there was the slamming thanks to her rounded drawn out fore-sections. Oh the slamming upwind in anything over force 4 or 5 got really old really quickly. Even blasting with her downwind grew old after about 10 hours or so. You couldn't leave her on the auto in those conditions as the hull was so twitchy so all the competent crew had to take turns hand steering her. On that trip over the north sea we had 3 days of force sevens over the stern quarter and we (the four of us) had to hand steer all of it in shifts. I was an exhausted wreck by the time the weather blew through.

But the thing that finally did for me and that boat was her windward performance in a blow. Those rounded fore sections together with the poorly setting self tacking jib and light beamy hull meant that in the kind of seastate you get with a blow of say force 5 and upwards the boat just got stopped when trying to go upwind. You just could not get that boat to go closer that 50 degrees off the wind in the sort of seas you get in a force five. By the time you got to force 7 she just would not go upwind at all. That is not only deeply frustrating, it is also dangerous (lee shore scenarios) and scary for crews unused to the deep blue sea. Having been caught out like this maybe 5 or so times I just knew this boat wasn't for us and how we sail.

I sold her a bought her antithesis and I have never been happier with a decision in my life. I now have a boat with a much drier and safer foredeck, that doesn't slam to windward and that will punch through heavy seas under sail and engine and thereby make ground to windward in all but that absolute worst conditions. A boat that with her balanced hull and longish fin and half skeg will track downwind with minimal input from the helm enabling her to sail like this on the autopilot day in day out.

She might not surf into the teens like my previous boat, but then surfing gets old fast on long trips.

She might not be just as close winded or easily driven in light airs either but she is no such here and I'd much rather give up 5 degrees of fair weather pointing for 15 to 30 degrees of pointing in a blow.

Basically, if you are doing fair weather cruising, sail only as a gentleman in heavy weather, and only do long trips well-crewed then modern plumb-bowed, fat bottomed, light displacement boats with deep fins for appendages are a blast.

If you are doing serious offshore cruising where you might have to make good to windward in a blow and against a gnarly sea and where you won't always have the crew necessary to helm the boat 24 7 i following seas, then those same boats are a PITA in my experience.

Know your program and buy the boat that best suits it. On my first go around I didn't follow that advice (despite 30 years of family cruising experience) and with all the costs involved in trading boats it proved an expensive mistake.

[argonauta1]

No worries, I circumnavigated in a Beneteau 440 and never took a wave in the cockpit either from the bow or the stern.

[Na Mara]

On weight at the bow I cannot but agree that many sailors over emphasise the importance of substantial ground tackle at the expense of overloading the bow. Not only does this increase uncomfortable pitching due to the large moment of inertia caused by an oversized anchor stored permanently on the roller and 100m of oversized chain, but I also believe it increases the likelihood of broaching when running from following seas. Basically, a heavier bow will plunge deeper into the back of wave and will take longer to rise out of it again. That creates a stronger pivot at the bow thereby making a broach more likely.

I have a 20kg Vulcan on my 12 ton Regina and 40m of 10mm chain. When we go offshore I take the anchor off the bow and store it aft. This I can do because the anchor isn't massively heavy and is relatively compact. The anchor this replaced was a 20kg CQR original to the boat. The previous owners had never gotten into trouble with that anchor in 25 years of sailing and the Vulcan is way superior kilo for kilo. Anchoring in a blow I let out the 40m of chain and then add as much rope bridal as the conditions require. This has the advantage of reducing weight at the bow, building in some shock absorption, and allowing stern to anchoring if sailing to the anchor becomes and issue. I judge this to be a more than adequate anchoring setup for all but hurricane conditions but it is also one that keeps weight out of the bow when sailing offshore thereby increasing safety and comfort when you need it most.

[DMF Sailing]

Originally Posted by Na Mara

I saw this thread and just had to pitch in as I had one of those plumb-bowed, light displacement, bulb-keeled, broad-transomed sailboats with self-tacking jib and full-battened main (Hanse 370e) and I sold her and I bought a conservative, medium displacement yacht with overhanging bow, veed fore-sections, longish fin keel, half-skeg rudder, conservative rig with overlapping genoa.

The overwhelming reason for that change was seakeeping ability.

The hanse was great in many ways. With the wind anywhere abaft the beam she was a rocket (I had her up into the teens multiple times). She had a big cockpit and her interior was possibly more spacious than that of the Regina 43 that I replaced her with despite her being fully 6 ft shorter. She was a great family boat where everyone could easily work the sails (with the exception of reefing the mainsail which no matter what I did was really heavy work) from the safety of the cockpit.

However, that self tacking jib was impossible to set well off the wind or on the wind passed its second reef and that plumb bow was indeed very wet. This second point is not such a problem normally as you just don't go to the bow in those conditions but occasionally you have to. I remember one occasion in particular when we were running before a force 7 in the north sea and the shackle on the tack of the jib broke. I had to go up there and tie the tack of the jib down. I remember sitting there on that foredeck lashing away between submersions. It took 90 minutes because of the intermittent green water over the deck. Not fun!! And then there was the slamming thanks to her rounded drawn out fore-sections. Oh the slamming upwind in anything over force 4 or 5 got really old really quickly. Even blasting with her downwind grew old after about 10 hours or so. You couldn't leave her on the auto in those conditions as the hull was so twitchy so all the competent crew had to take turns hand steering her. On that trip over the north sea we had 3 days of force sevens over the stern quarter and we (the four of us) had to hand steer all of it in shifts. I was an exhausted wreck by the time the weather blew through.

But the thing that finally did for me and that boat was her windward performance in a blow. Those rounded fore sections together with the poorly setting self tacking jib and light beamy hull meant that in the kind of seastate you get with a blow of say force 5 and upwards the boat just got stopped when trying to go upwind. You just could not get that boat to go closer that 50 degrees off the wind in the sort of seas you get in a force five. By the time you got to force 7 she just would not go upwind at all. That is not only deeply frustrating, it is also dangerous (lee shore scenarios) and scary for crews unused to the deep blue sea. Having been caught out like this maybe 5 or so times I just knew this boat wasn't for us and how we sail.

I sold her a bought her antithesis and I have never been happier with a decision in my life. I now have a boat with a much drier and safer foredeck, that doesn't slam to windward and that will punch through heavy seas under sail and engine and thereby make ground to windward in all but that absolute worst conditions. A boat that with her balanced hull and longish fin and half skeg will track downwind with minimal input from the helm enabling her to sail like this on the autopilot day in day out.

She might not surf into the teens like my previous boat, but then surfing gets old fast on long trips.

She might not be just as close winded or easily driven in light airs either but she is no such here and I'd much rather give up 5 degrees of fair weather pointing for 15 to 30 degrees of pointing in a blow.

Basically, if you are doing fair weather cruising, sail only as a gentleman in heavy weather, and only do long trips well-crewed then modern plumb-bowed, fat bottomed, light displacement boats with deep fins for appendages are a blast.

If you are doing serious offshore cruising where you might have to make good to windward in a blow and against a gnarly sea and where you won't always have the crew necessary to helm the boat 24 7 i following seas, then those same boats are a PITA in my experience.

Know your program and buy the boat that best suits it. On my first go around I didn't follow that advice (despite 30 years of family cruising experience) and with all the costs involved in trading boats it proved an expensive mistake.

Thanks for this post. Not that I didn't appreciate all the other opinions expressed and knowledge shared, but are the person I was waiting for when I wrote the original post, because the passage I am planning is on a slightly larger Hanse, which displayed all the characteristics you mentioned last time I cruised on it.

And not that I won't love my upcoming cruise, but I would never buy this boat.