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Old 01-20-2021, 07:58 AM   #1
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SD v FD in weather

Yesterday was a interesting day. We looked at a one year old North Pacific 45. We also put in an offer on a Nordie. The NP45 was drop dead gorgeous and wife enthralled by the interior. Quality of build seemed excellent as well. But on the drive home she noted. The semi displacement hull, lack of stabilization, need for knee pads and risk of crawling around a hot engine should something go wrong down there in a seaway.
The only two times we’ve been declared overdue (and once SARS sent out) have been coastal. Both times decades ago before current increased weather forecasting improvements. Both times pushed by schedules. Still, even in recent years have been caught by weather. Believe your judgment and view of the world is effected by your experience. So believe if you’re going even to do just long hop coastal eventually you’re going to see weather. Line squalls, pop up T-storms and the like at a minimum.
So here’s the question. Are active techniques different for SD v FD in weather? If so how? Specifically what techniques do you use? At what point and how do you employ passive techniques such as sea anchors and drogues? What are your feelings about vessel design for vessels doing multi day near shore (<50nm) transits?
We passed on considering any SD boat as our next cruising platform. But note in our search the overwhelming predominance of cruising boats are SD. Is our thinking way off base?
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Old 01-20-2021, 08:33 AM   #2
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IMO, you need some form of stabilization (,active or passive) on a power boat if you're passage making (greater than 3 day crossing). My semi displacement hull is fine for a one or two day crossing and doesn't do badly until in moderate beam seas. If I were going to Bermuda (which I wouldn't) I would be prepared to keep the bow into the seas until the weather passed as a larger beam seas past a certain point, make the roll miserable.

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Old 01-20-2021, 08:38 AM   #3
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With SD and adequate engine power, you have more options provided fuel range isn't an issue. Simply because you have a wider range of speeds to choose from. If dealing with beam seas or other rolly conditions, speeding up a bit above hull speed will usually make things a lot more stable with an SD hull. Given enough power, a short enough distance to somewhere to hide and enough warning, you may have the option to turn and run before the weather hits you (but don't count on this). At a minimum, the ability to go faster may mean you're in unpleasant conditions for a shorter period of time.

The best tactics to use in a given set of conditions will depend just as much on the specific hull in question as it does on SD vs FD. In general, a more full, buoyant bow will ride a bit worse (but often dryer) going into steep seas. Going down-wind, that more full bow will be less likely to dig in and bow steer. A finer, more pointy bow will pitch a bit less and cut through waves better going up-wind, but will be more likely to take water over the decks when things get ugly. And it'll be more likely to dig into a wave going down wind.

In the realm of coastal cruising where you're always within, say, 8 hours of safe harbor, the vast majority of 40+ foot boats with enough fuel range to do more than hop from fuel dock to fuel dock will be capable enough to handle the short term weather events that aren't always predictable. The really bad weather is typically predicted and avoidable. FD designs (especially stabilized) will often be more comfortable when it's ugly out, but neither is likely to approach its true limits in coastal use.

Having a boat with a crawl-in engine room, I find I'm much more stable and can move around more easily by squatting and sitting on my feet rather than kneeling. Pay careful attention to the layout to determine how often you're likely to need to crawl into the tighter areas. And think about getting in there with things moving around and whether there are any danger points (like exposed engine belts to crawl past).
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Old 01-20-2021, 08:46 AM   #4
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Ted you have a lovely boat. That company makes a Rolls Royce of a boat. In sail both the 44 and 48 are still highly desired. What is your technique for weather? Stabilization has no effect of AVS just comfort. Given that and desire for comfort at what point will you run with the seas if that’s closer to your intended heading or decide to jog into them?
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Old 01-20-2021, 09:01 AM   #5
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RS Dashew has written fascinating stuff about his experience and techniques using the FPB as a platform. Think they’re a different beast where speed does keep you going as fast as the wave train so running remains safe. I wonder how much of this is really applicable to our boats. The difference between 7 and 12 knots still means exposure in many coastal settings we encounter. Doesn’t it mean at a certain wave height and period doing a rumline to the nearest port isn’t an option? Just crossing the Gulf of Maine, or the NJ coast where with a easterly means the entrances to the few available harbors are problematic or so many other settings (pop up T storms as an example) which are are hyper local and unpredicted. Does this impact how you use your boat? Does it restrict you in any meaningful way?
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Old 01-20-2021, 09:21 AM   #6
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RS Dashew has written fascinating stuff about his experience and techniques using the FPB as a platform. Think they’re a different beast where speed does keep you going as fast as the wave train so running remains safe. I wonder how much of this is really applicable to our boats. The difference between 7 and 12 knots still means exposure in many coastal settings we encounter. Doesn’t it mean at a certain wave height and period doing a rumline to the nearest port isn’t an option? Just crossing the Gulf of Maine, or the NJ coast where with a easterly means the entrances to the few available harbors are problematic or so many other settings (pop up T storms as an example) which are are hyper local and unpredicted. Does this impact how you use your boat? Does it restrict you in any meaningful way?

There's absolutely a point where conditions are bad enough (in any boat) that some courses become off limits. Not necessarily because you can't, but because you'd be too miserable and won't want to. How much speed helps you beyond stabilizing the ride will depend on the conditions and how fast the boat in question can cruise. Sometimes an extra couple of kts is enough to make a big difference, sometimes it isn't.

On my own boat (which is a full planing hull that cruises around 17 kts, so faster than most of the SD boats on here and a little worse behaved at low speeds), with the steep crap we get on the Great Lakes, I tend to avoid beam seas above 2 - 3 feet. Once they're over 1.5 feet or so, it's time to get up on plane, as the motion is more comfortable (more of a series of tilt, sit there for a minute, tilt the other way rather than a constant rolling).

For me, Head seas are fine to 3 - 4 feet up on plane (more if they're not steep). If they're steep, the pitching can get excessive at low speed as the bow is very buoyant (to the point where at low speed it goes over the top at all costs, never through a wave). Going down-wind, I haven't found the limit. Running in 3 - 4 downwind up on plane is comfy. Just a light touch on the steering and just a matter of "climb, pitch down over the top, surf, repeat".

I've come back in with the wind blowing straight up the river, which stacks up the waves badly against the small river current in the entrance channel between the piers. I remember one day of 2 - 3 footers on the lake, but 4 - 5 in the first bit of the entrance channel. I just kept a hand on the throttles at about 9 kts and rode the trough between 2 waves. Took a little effort for speed adjustments, but perfectly comfortable as if we were in flat water. In a situation like that, coming into an inlet that's bit sloppy, I'd say an SD with decent power will be easier to handle than a slow FD boat unless the FD is of a shape that really likes following seas.

Many SD trawlers have a bit finer bow than I do, so the downwind performance may not be quite as good, but the pitching shouldn't be as bad going upwind at lower speeds.

The link contains a pair of videos.One is running up on plane in some slightly confused small seas (at about 16.5 - 17 kts). Hard to really see the waves in the video, but they're off the port bow and a bit behind the port beam (after a wind shift). I'd say probably about 1 foot for both wave trains, wind just forward of the port beam. The other video is 1.5 - 2 footers off the stbd bow, running about 6.5 kts. Wind was off the stbd bow in this one. Unfortunately I don't have much video of us running, so nothing in worse conditions.

Comparing the 2 videos, you can see that motion becomes much more damped at higher speeds. Even an SD a knot above hull speed will gain a good bit of damping compared to running slowly. The lift from the flatter parts of the hull does quite a bit in that respect.


Planing video: https://photos.app.goo.gl/h8QFCMz791d3X1s4A

Slow video: https://photos.app.goo.gl/7DLrJXtCvmU7xUEi6
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Old 01-20-2021, 09:27 AM   #7
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Ted you have a lovely boat. That company makes a Rolls Royce of a boat. In sail both the 44 and 48 are still highly desired. What is your technique for weather? Stabilization has no effect of AVS just comfort. Given that and desire for comfort at what point will you run with the seas if that’s closer to your intended heading or decide to jog into them?
Thank you! I like it.

I don't consider my boat even close to a modest passage maker. It will handle 7'+ on the bow with reduced speed, and it can run with modest speed seas in relative comfort with the autopilot and large rudder keeping the boat on course. Where it gets scary is when the seas go faster than the hull and pass underneath. The boat doesn't have the nice rounded buoyant stern of a Kadey Krogen 42 and lacks adequate stern deck drainage should a wave dump water over the cap rail. I've never had an incident with water on the back deck, but it's unnerving to see seas above the stern cap rail because of the drainage issue.

To answer your question, I do coastal cruising and avoid bad weather. When I have gotten caught in it, I can do maybe 30 degrees either side of head on or go with them. My square stern needs to be square to the seas or I may find myself taking the next one on the beam.

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Old 01-20-2021, 10:28 AM   #8
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Hey Hippo - good to hear you found a solid candidate to make an offer. Keep us posted at appropriate times.

I know of no powerboat that has a drogue aboard let alone have deployed one. I'm sure they're out there - ex-sailor types who bought a Nordhavn or something. I just have never heard of one. Suffice to say, I can offer no color commentary.

The Dashew FPB is a different animal. Long, narrow, and fast. Ability to bridge waves and pierce those it encounters. Reserve buoyancy is not a design criteria.

Leaving aside FPB, there's a point in weather where all boats move at displacement speeds. And there's a point where they will need to slow down, bear-off, or both. If reasonably watertight, higher quality planing boats are not bad sea boats as they tend to be low and wide with a lot of form stability - if you can keep enough speed to keep flow past the rudders and steerage. A/P works triple-time.

I guess I'm still a bit confused over the discussion on freak thunderstorms and cells. Yes, they will undoubtedly happen. Yes, weather will be worse than forecast. But sea state is function of fetch, wind speed, and duration. I simply don't recall being surprised by 40kts for more than an hour, maybe two - localized weather means limited fetch, and duration is too short to create much disturbance. Now, I do recall 30-kts sustained for a couple days that built 8-foot chop coming up the Caribbean from Panama Canal, and similar coming up the Baja, but those were decisions, not surprises (well, I expected 20-25 and got the upper end of 25-30).

As far as being within 8-hours of a port, it really depends on where you're cruising. East coast US - absolutely. West Coast, well.......sometimes, but often not. Anchorages are mostly open roadsteds and are highly weather dependent, as are the ports themselves. Between Los Arcos (the tip of Baja) and Tatoosh Island and the entrance of the Straights of Juan de Fuca is over 2000 nms. Setting aside the hook of Southern California, there are probably under a dozen all-weather ports/anchorages (a guess).

So Hippo - for me, when headseas get more than about 5-foot of short chop, most boats need to throttle-back to something below displacement speed. At some point around 6-7 feet, bearing off 20-degrees becomes comfortable. Normally just for a few hours for the weather system to pass, then you're off and running again. At least that's been my experience, but I haven't crossed an ocean, but have many, many 5+ day non-stop runs on open water.

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Old 01-20-2021, 11:46 AM   #9
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Old 01-20-2021, 12:13 PM   #10
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I know of no powerboat that has a drogue aboard let alone have deployed one. I'm sure they're out there - ex-sailor types who bought a Nordhavn or something. I just have never heard of one. Suffice to say, I can offer no color commentary.
I think the difference is more between stabilized vs. not stabilized than SD vs FD. FD usually have round bilges and will roll more easily but slower. There is little difference in AVS. My SD definitely stabilizes when run a little above hull speed, FD do not have that opportunity.

Regarding drogues and sea anchors, parachute sea anchors have been routinely used for many decades by fishermen to ride out rough weather or simply get a good night's sleep. I just bought one for my boat, not because I'm going offshore into weather, but in the event of power failure. If the engine quits, it does not take much of a seaway to make things very uncomfortable as the boat lies ahull (beam to the seas). This can happen in relatively protected water. And you are head down, down below trying to work on the engine - a recipe for sea sickness if there ever was one. Last year we even heard a mayday call from a disabled powerboat where they were so uncomfortable they wanted off, even without any immediate danger. The parachute would keep the bow more or less into the seas, and make things more tolerable as you try to get sorted out. Stabilizers are probably useless in that situation unless gyro and some way to power it with the engine out.
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Old 01-20-2021, 12:25 PM   #11
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Regarding drogues and sea anchors, parachute sea anchors have been routinely used for many decades by fishermen to ride out rough weather or simply get a good night's sleep. I just bought one for my boat, not because I'm going offshore into weather, but in the event of power failure. If the engine quits, it does not take much of a seaway to make things very uncomfortable as the boat lies ahull (beam to the seas)
I had not heard this before. It's a good idea.

How big is a chute-anchor stowed?

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Old 01-20-2021, 12:41 PM   #12
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I have a Para Tech sea anchor on my boat that I use frequently for fishing but have also used to lay in weather. My boat is round bilge full displacement hull of 26 feet and weighs about 7000 pounds, my sea anchor is 12 feet in diameter and stores and deploys from a bag about the size of a small backpack. The rode is 600 feet of 3/8 nylon which takes up about the same space as the anchor.
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Old 01-20-2021, 01:02 PM   #13
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With all the weather forecasting these days how does a costal cruiser get caught in bad weather?
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Old 01-20-2021, 01:09 PM   #14
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With all the weather forecasting these days how does a costal cruiser get caught in bad weather?
You've never seen a weather forecast that turned out to be wrong?
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Old 01-20-2021, 01:10 PM   #15
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Weather forecasts are definitely not always accurate. However, in a coastal context, you're usually talking "forecast was decent, actual conditions were crap" rather than "forecast was good, actual weather was survival conditions"
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Old 01-20-2021, 01:13 PM   #16
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With all the weather forecasting these days how does a costal cruiser get caught in bad weather?
Not sure who this is directed to, but I tend to agree with you. I am pretty comfortable running with a rolling 72-hour forecast. Yes, there are localized weather events (forecast and unforecast) that can be severe, but lack the duration to develop dangerous seas. There is no way I'd head 3-days into open water with sustained 30-kts forecast over the period which would result in 3-meter chop. But going through a patch of 4-hours of 30-kts (builds to 1.0-1.5 meter chop) to get to nirvana on the other side is an acceptable tradeoff even though it's 4-hours of slop. It also depends on what you define as bad weather. Also means you could guess wrong and it's 6-hours of 35+ kt winds.

The idea of a Sea Anchor that piqued my interest is the notion of a failed engine. Along the Pacific Coast, prevailing winds are from the NW so you are almost always staring at a lee shore in the event of an engine failure. Sea Anchor buys time - a precious commodity. They aren't very expensive and they don't take much room.

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Old 01-20-2021, 01:16 PM   #17
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Weather forecasting is better than in the past, but can still be off by hours or days! Just last week a wind event forecast for about thirty knots blew up to gusts at 70 knots (with gusts to 100 knots recorded in the mountains). It happens! Local forecasts are made more complicated by geography. Here in the NW (SE for Alaska and British Columbia), boating is done amid and next to mountains. Mountains have profound, localized effect on winds.

(Steps off soapbox)
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Old 01-20-2021, 01:18 PM   #18
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I've seen a predicted 10 to 15kts that came as 15 to 25kts with gusts to 30 more than once where I am. Especially for someone that's cruising away from their home waters local conditions can vary greatly depending on depth, bottom contour, tide and landform.
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Old 01-20-2021, 01:19 PM   #19
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You've never seen a weather forecast that turned out to be wrong?
Rslifkin put it well - not so wrong that it goes to survival condition unexpectedly. Sea state is affected by distant pressure systems, but the scary stuff is driven by winds. Takes fetch, duration, and intensity. Within a 72-hour window, it's common to get surprised by intensity, but lacks duration and fetch to build to dangerous levels. Not saying it's a comfortable, but to rslifkin's point, not really survival conditions......unless something else goes.

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Old 01-20-2021, 01:22 PM   #20
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Been reading about and talking with power cruising couples. For a N40-43 usually 16’ to 18’ suffices. Comparing different designs and with my prior experience with the Jordan series drogue at present favor the Fiorentino design. With that one there’s at least the possibility of being able to retrieve it and more likelihood it will deploy correctly and stay open. Whereas drogues make great sense for sail and as a option if steering fails see warps using floating nylon as a makeshift intermittent option for power if a sea anchor isn’t present.
As an aside will relate a few experiences.
We had just crossed the race with intention of going to Sag. ( these places are very coastal with land on both sides at the end of Long Island sound). Gribs were benign as were all forecasts. Tide and current was against wind during the T storm. Waves were 5-7’ with occasional higher ones as (? 9-12’) they reflected and deflected off the land. Although in sight of the entrance bouys to Sag ended up turning toward Connecticut. Some gusts went well over 50. So respectfully disagree. No fetch, brief episode just hours but still most definitely sparky. Would add I had no desire to enter a channel I never was in to go to a marina or anchorage I never used during rapidly building conditions.
Peter you know you can SEE weather a long time off when offshore or ocean. Only concern is microbursts or white squalls. Much talked about but (knock on wood) a rare event. Continue to feel hyper local events in coastal or near shore settings are a real concern. The one time SARS was sent out for us was coastal as well. Just going from Southwest harbor to Duxbury. Agree that’s very unlikely to occur again as that was due to several weather bouys not reporting and before current accuracy of forecasting. But again a coastal occurrence. With covid reporting from commercial aircraft and ships declined for awhile. Believe this did impact forecasting to some degree. An EMF burst or more likely an intentional hack although of low probability can occur. More likely is hyper local weather. In any case like running aground it’s not if but when. Sooner or later you will see sparky weather.
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