Appendix [[3]] â Comments upon MGN 328 â Operational Guidance ...
Appendix [[3]] – Comments upon MGN 328 – Operational Guidance
The high-speed Masters in the peer review team compliment the MCA Project Team for this focused operational guidance, which is the first of its kind anywhere within the high-speed community. They found the material presented in this Guidance Note accurate in terms of their operational experiences. It provides a concise and to-the-point overview of the dynamic phenomena of greatest concern to operators of high-speed ships and craft. The related MCA Informational Film: “High Speed Craft – Control in Following Seas," clearly shows the dramatic nature of these phenomena. Used together, they can provide operators a very effective introduction to the phenomena and how to deal with them. The operational component of the peer review team are experienced U.S. high-speed commercial catamaran Masters who were brought into this project because of their first-hand experience with a bow or deck dive. The following comments may therefore appear skewed to the topic of bow-diving ahead of all other behavior characteristics. Nevertheless, the team did consider all of the dynamic phenomena included in MGN 328 (M). Regarding Paragraph 1.1: The high-speed Masters in the peer review team noted that severe seas alone do not guarantee being immediately affected. On the other hand, calm to moderate seas in combination with a large ocean swell can lead to these dynamic effects occurring. One high-speed Master in the peer review team noted that operators must be aware of and take into account the sea conditions and wave patterns of their local operating area. For example, differences between the ports of the east and west coasts of the United States as well as differences in local wind patterns, water depth and fetch all contribute to route-specific and unique sea states. Some success has been experienced by U.S. operators in partnering with the National Oceanographic and Atmospheric Administration (NOAA) to install weather buoys in key locations (where high-speed ferries run) so that real-time wave data and sea conditions can be monitored ashore, then transmitted as necessary to vessel Masters on the bridge. The result is that Masters can receive real-time data while in transit, such as swell height and period ahead and behind them. Monitoring these trends allows them to adjust their route planning and gives advance notice of changing sea conditions and when and where they can be expected.
The high-speed Masters in the peer review team compliment the MCA The
mcc, USCG – 9/14/09
Appendix [[3]] – Comments upon MGN 328 – Operational Guidance
Regarding Paragraph 1.4: One high-speed Master in the peer review team noted the limitations of current instruments in their ability to assist with the avoidance of dynamic problems. For instance, although some ride control systems, if installed, have alarms that can be set to detect sudden vertical accelerations, it is important to understand what available instruments are NOT able to tell as well as what they can tell you. Other high-speed Masters confirmed the need to be sensitive to variations in vessel speed when traveling down-sea, as those changes are the first indication of surging. They further confirmed the practice and the accuracy of closely watching vessel speed on GPS to track this condition, especially at night. Regarding Section 3: The high-speed Masters support the descriptions of the critical craft behaviors described, noting that it is crucial for the mariner to recognize when he/she is in conditions that are conducive to causing the craft behavior described. Situational awareness is paramount. Further, one high-speed Master in the peer review team commented that with a high-speed catamaran in head or difficult seas, the need for situational awareness is acute. However, the conventional wisdom of putting the seas on the vessel’s stern for the resultant smoother ride can give a false sense of security that breeds complacency, in a situation where awareness needs to be keenest—operating down-sea. Finally, as described throughout Section 3, the peer review team agrees that a high-speed Master must know his/her vessel speed in relationship to wave height, speed and period.
Regarding Paragraph 1.4: One high-speed Master in the peer review team
mcc, USCG – 9/14/09
Appendix [[3]] – Comments upon MGN 328 – Operational Guidance
Regarding paragraph 3.3: Beyond instrumentation, the high-speed Masters in the peer review team indicated that they became very sensitive to how their vessels “feel” and the characteristics they exhibit building up to a potential bow diving situation. Further, the high-speed Masters confirmed that when traveling at or below the speed of the wave the situation (bow diving) can build slowly and then happen suddenly with little time to react. Recalling previous comments on situational awareness, their advice based on experience was: “don’t get yourself into a situation that you have to get out of.” Although beyond the scope of Research Study 502, the high-speed Masters stated that their experience has shown that bow diving can occur rapidly without the warning signs of trapping, surging and surfing, when traveling at speeds greater than the waves in a short steep sea. Moreover, it is not necessary for the vessel waterline length and the wave length to be close to equal. The situation can occur when driving over a wave crest, down the wave front, into the trough and into the back of the next wave. Consequences vary with speed, wave height and inherent vessel reserve buoyancy characteristics.
Regarding paragraph 3.3: Beyond instrumentation, the high-speed Masters in
mcc, USCG – 9/14/09
Appendix [[3]] – Comments upon MGN 328 – Operational Guidance
Regarding paragraph 3.4: One high-speed Master in the peer review team noted that catamarans tend to pull to the opposite side of whichever bow is deepest in a following sea (the start of a broach), but that with water jets this is easy to control by changing throttle settings and even lowering the buckets on the hull opposite the turn direction and applying reverse thrust. Most felt, however, that it depends on the capabilities of the propulsion control system installed, with the above techniques increasingly difficult as vessel speed increases. With respect to waterjet propulsion, another high-speed Master noted that anytime power is backed off you will lose some degree of directional control. If thrust is pulled back too quickly on a big enough wave, it can lead to a broach that can be catastrophic. The high-speed Masters all agreed that with waterjet propulsion they are always mindful of the fact that the units are not rudders and steerage is only maintained simultaneously with thrust. No matter the type of propulsion, steerage must be maintained to keep or regain control. Sometimes that may require more aggressive action in a following sea, such as altering course, increasing thrust and “powering out” to the side of and down the trough of a wave. One high-speed Master commented that contingency planning is mentally ongoing when traveling down-sea so that you always “give yourself a back door” out of a situation. He stressed the importance of keeping both hulls in the water, noting that you can’t “pull out” on only one hull. Regarding paragraphs 3 and 4: One high-speed Master in the peer review team noted that reducing speed while changing course to “tack” down-sea is effective for maintaining vessel control. He also stated his opinion that catamarans with planing hulls give better and faster response than round bilge displacement hulls. All of the high-speed Masters felt that companies operating these craft should include a full explanation of these operational limitations and behavioral characteristics in the training and certification programs for their Masters.
Regarding paragraph 3.4: One high-speed Master in the peer review team
mcc, USCG – 9/14/09
Appendix [[3]] – Comments upon MGN 328 – Operational Guidance
Regarding paragraph 4.5: Although beyond the scope of this study, the highspeed Masters in the peer review team noted that operators should be aware that ride control systems (RCS) have some effect when craft behavior becomes critical. They felt the limitations as well as capability of the installed RCS must be understood, so it is neither under- nor over-utilized. Most agreed that RCS are often intentionally “turned down” or “locked off” when running down-sea to avoid a “set it and forget it” mindset. The high-speed Masters noted that when ride quality and control do not improve with continued RCS adjustments, then speed change is necessary. One high-speed Master confirmed using the RCS to advantage down-sea by switching to manual mode, setting the bow for maximum lift, and retracting the stern flaps “full up.” This places the vessel in an active “squat” that allows higher speeds and better control down-sea as a result of increased trim by the bow and the maintaining of sufficient waterjet immersion. Regarding paragraph 5: One high-speed Master in the peer review team noted: “Speed kills. You have to slow down and respect the conditions you are operating in, while simultaneously conducting TRAINING, TRAINING and more TRAINING.” There is no statement in the summary about the importance of mandatory high-speed operator training. The forms of “critical craft behavior” in following and stern quartering seas as described in this MGN are applicable and should be included in any HSC Code type-rating or domestic high-speed training regime. Regarding paragraph 5.1, the high-speed Masters agreed that night operations are more challenging. They confirmed their sensitivity to audible cues of changing conditions in a following sea, such as shuddering of the hull. Operator vigilance and timely action at the first indication of slowly increasing bow down/stern lifting attitude is necessary to avoid the potential of bow diving. This may include frequent evasive measures such as turning off-course, even at the expense of passenger comfort due to increasing roll.
Regarding paragraph 4.5: Although beyond the scope of this study, the high-
mcc, USCG – 9/14/09
Appendix [[3]] – Comments upon MGN 328 – Operational Guidance
Regarding Table 1: The high-speed Masters in the peer review team did not find this tabular presentation user-friendly in the wheelhouse. One opined that some type of “slide rule” (such as the Weems and Plath speed/time/distance wheel) would be helpful, noting that some simple, visual presentation of vessel speed/relative sea direction/wave height might further enhance quick recognition and understanding. That said, the high-speed Masters have, since its publication, made good use of MGN 328(M) in combination with MCA Information Film: “High Speed Craft – Control in Following Seas” to raise their companies' awareness and to train other high-speed Masters. They understand MCA's concerns regarding copyright but consider the Information Film one of the best training tools currently available and suggest that MCA revisit the limited distribution rule with the objective of modifying the current DVD so that it may be given the widest possible unrestricted distribution.
Regarding Table 1: The high-speed Masters in the peer review team did not
mcc, USCG – 9/14/09
Appendix [[3]] – Comments upon MGN 328 – Operational Guidance
Regarding Figure 1 and Table 2: Several of the high-speed Masters in the peer review team found Table 2 the more user-friendly presentation. These Masters confirmed that the numbers presented for coastal wave speeds associated with significant wave heights are in fact representative of their experience. One high-speed Master noted that among the hardest concepts to grasp when operating a high speed catamaran are those of wave height, wave speed and wave period and their combinations that can occur . Table 2 is useful for relating wave height and speed. Another high-speed Master in the peer review team further confirmed the need to be aware of wave period as well as wave speed. Based on a postbow dive casualty analysis in 1999, his company’s high-speed Masters are trained to time the period between wave peaks regularly when underway. Their analysis concluded that regardless of other factors such as wave speed and height, a five-second wave period equates to a wave length of approximately 40 meters, which is generally the size (waterline length) of the high-speed catamarans in that company’s fleet. The 1999 analysis cited Maritime Safety Committee Circular 707: “IMO Guidance to the Master for Avoiding Dangerous Situations in Following and Quartering Seas” dated 19 October 1995, which indicates that wave period can be measured by stopwatch. This is a quick and easy way for high-speed Masters to know when they must take corrective action, especially when operating at speed down-sea.
Regarding Figure 1 and Table 2: Several of the high-speed Masters in the
mcc, USCG – 9/14/09
Appendix [[3]] – Comments upon MGN 328 – Operational Guidance
However, wave period is not addressed in the text of MGN 328 (M) or in figure 1 or Table 2. In order to include wave period in this discussion, the figure to the right shows the relationship between wave length, speed and period in the open ocean. An operator can use a stopwatch to estimate the wave period, then enter the figure on the lefthand side with that value and read the wave speed on the right or the wave length on the bottom. Knowing his boat length and speed relative to the length and speed of the waves, he can then decide whether to speed up or slow down or change course to avoid a potential problem. It is important to note, however, that this can change in coastal waters. As the water depth decreases, wave length and speed both decrease (and wave height increases). Wave period can vary somewhat, up or down, from the open ocean case. In fact, other high-speed Masters in the peer review team indicated that in their operational experience, factors such as water depth and current also influence wave formation, with the inference that wave behavior may be more complex than Figure 1 and Tables 1 and 2 would suggest, thereby giving users misleading information.
This table corresponds with the preceding figure. Start on the top line with the wave period, then read wave speed and length directly below.
mcc, USCG – 9/14/09
The high-speed Masters in the peer review team compliment the MCA Project Team for this focused operational guidance, which is the first of its kind anywhere within the high-speed community. They found the material presented in this Guidance Note accurate in terms of their operational experiences. It provides a concise and to-the-point overview of the dynamic phenomena of greatest concern to operators of high-speed ships and craft. The related MCA Informational Film: “High Speed Craft – Control in Following Seas," clearly shows the dramatic nature of these phenomena. Used together, they can provide operators a very effective introduction to the phenomena and how to deal with them. The operational component of the peer review team are experienced U.S. high-speed commercial catamaran Masters who were brought into this project because of their first-hand experience with a bow or deck dive. The following comments may therefore appear skewed to the topic of bow-diving ahead of all other behavior characteristics. Nevertheless, the team did consider all of the dynamic phenomena included in MGN 328 (M). Regarding Paragraph 1.1: The high-speed Masters in the peer review team noted that severe seas alone do not guarantee being immediately affected. On the other hand, calm to moderate seas in combination with a large ocean swell can lead to these dynamic effects occurring. One high-speed Master in the peer review team noted that operators must be aware of and take into account the sea conditions and wave patterns of their local operating area. For example, differences between the ports of the east and west coasts of the United States as well as differences in local wind patterns, water depth and fetch all contribute to route-specific and unique sea states. Some success has been experienced by U.S. operators in partnering with the National Oceanographic and Atmospheric Administration (NOAA) to install weather buoys in key locations (where high-speed ferries run) so that real-time wave data and sea conditions can be monitored ashore, then transmitted as necessary to vessel Masters on the bridge. The result is that Masters can receive real-time data while in transit, such as swell height and period ahead and behind them. Monitoring these trends allows them to adjust their route planning and gives advance notice of changing sea conditions and when and where they can be expected.
The high-speed Masters in the peer review team compliment the MCA The
mcc, USCG – 9/14/09
Appendix [[3]] – Comments upon MGN 328 – Operational Guidance
Regarding Paragraph 1.4: One high-speed Master in the peer review team noted the limitations of current instruments in their ability to assist with the avoidance of dynamic problems. For instance, although some ride control systems, if installed, have alarms that can be set to detect sudden vertical accelerations, it is important to understand what available instruments are NOT able to tell as well as what they can tell you. Other high-speed Masters confirmed the need to be sensitive to variations in vessel speed when traveling down-sea, as those changes are the first indication of surging. They further confirmed the practice and the accuracy of closely watching vessel speed on GPS to track this condition, especially at night. Regarding Section 3: The high-speed Masters support the descriptions of the critical craft behaviors described, noting that it is crucial for the mariner to recognize when he/she is in conditions that are conducive to causing the craft behavior described. Situational awareness is paramount. Further, one high-speed Master in the peer review team commented that with a high-speed catamaran in head or difficult seas, the need for situational awareness is acute. However, the conventional wisdom of putting the seas on the vessel’s stern for the resultant smoother ride can give a false sense of security that breeds complacency, in a situation where awareness needs to be keenest—operating down-sea. Finally, as described throughout Section 3, the peer review team agrees that a high-speed Master must know his/her vessel speed in relationship to wave height, speed and period.
Regarding Paragraph 1.4: One high-speed Master in the peer review team
mcc, USCG – 9/14/09
Appendix [[3]] – Comments upon MGN 328 – Operational Guidance
Regarding paragraph 3.3: Beyond instrumentation, the high-speed Masters in the peer review team indicated that they became very sensitive to how their vessels “feel” and the characteristics they exhibit building up to a potential bow diving situation. Further, the high-speed Masters confirmed that when traveling at or below the speed of the wave the situation (bow diving) can build slowly and then happen suddenly with little time to react. Recalling previous comments on situational awareness, their advice based on experience was: “don’t get yourself into a situation that you have to get out of.” Although beyond the scope of Research Study 502, the high-speed Masters stated that their experience has shown that bow diving can occur rapidly without the warning signs of trapping, surging and surfing, when traveling at speeds greater than the waves in a short steep sea. Moreover, it is not necessary for the vessel waterline length and the wave length to be close to equal. The situation can occur when driving over a wave crest, down the wave front, into the trough and into the back of the next wave. Consequences vary with speed, wave height and inherent vessel reserve buoyancy characteristics.
Regarding paragraph 3.3: Beyond instrumentation, the high-speed Masters in
mcc, USCG – 9/14/09
Appendix [[3]] – Comments upon MGN 328 – Operational Guidance
Regarding paragraph 3.4: One high-speed Master in the peer review team noted that catamarans tend to pull to the opposite side of whichever bow is deepest in a following sea (the start of a broach), but that with water jets this is easy to control by changing throttle settings and even lowering the buckets on the hull opposite the turn direction and applying reverse thrust. Most felt, however, that it depends on the capabilities of the propulsion control system installed, with the above techniques increasingly difficult as vessel speed increases. With respect to waterjet propulsion, another high-speed Master noted that anytime power is backed off you will lose some degree of directional control. If thrust is pulled back too quickly on a big enough wave, it can lead to a broach that can be catastrophic. The high-speed Masters all agreed that with waterjet propulsion they are always mindful of the fact that the units are not rudders and steerage is only maintained simultaneously with thrust. No matter the type of propulsion, steerage must be maintained to keep or regain control. Sometimes that may require more aggressive action in a following sea, such as altering course, increasing thrust and “powering out” to the side of and down the trough of a wave. One high-speed Master commented that contingency planning is mentally ongoing when traveling down-sea so that you always “give yourself a back door” out of a situation. He stressed the importance of keeping both hulls in the water, noting that you can’t “pull out” on only one hull. Regarding paragraphs 3 and 4: One high-speed Master in the peer review team noted that reducing speed while changing course to “tack” down-sea is effective for maintaining vessel control. He also stated his opinion that catamarans with planing hulls give better and faster response than round bilge displacement hulls. All of the high-speed Masters felt that companies operating these craft should include a full explanation of these operational limitations and behavioral characteristics in the training and certification programs for their Masters.
Regarding paragraph 3.4: One high-speed Master in the peer review team
mcc, USCG – 9/14/09
Appendix [[3]] – Comments upon MGN 328 – Operational Guidance
Regarding paragraph 4.5: Although beyond the scope of this study, the highspeed Masters in the peer review team noted that operators should be aware that ride control systems (RCS) have some effect when craft behavior becomes critical. They felt the limitations as well as capability of the installed RCS must be understood, so it is neither under- nor over-utilized. Most agreed that RCS are often intentionally “turned down” or “locked off” when running down-sea to avoid a “set it and forget it” mindset. The high-speed Masters noted that when ride quality and control do not improve with continued RCS adjustments, then speed change is necessary. One high-speed Master confirmed using the RCS to advantage down-sea by switching to manual mode, setting the bow for maximum lift, and retracting the stern flaps “full up.” This places the vessel in an active “squat” that allows higher speeds and better control down-sea as a result of increased trim by the bow and the maintaining of sufficient waterjet immersion. Regarding paragraph 5: One high-speed Master in the peer review team noted: “Speed kills. You have to slow down and respect the conditions you are operating in, while simultaneously conducting TRAINING, TRAINING and more TRAINING.” There is no statement in the summary about the importance of mandatory high-speed operator training. The forms of “critical craft behavior” in following and stern quartering seas as described in this MGN are applicable and should be included in any HSC Code type-rating or domestic high-speed training regime. Regarding paragraph 5.1, the high-speed Masters agreed that night operations are more challenging. They confirmed their sensitivity to audible cues of changing conditions in a following sea, such as shuddering of the hull. Operator vigilance and timely action at the first indication of slowly increasing bow down/stern lifting attitude is necessary to avoid the potential of bow diving. This may include frequent evasive measures such as turning off-course, even at the expense of passenger comfort due to increasing roll.
Regarding paragraph 4.5: Although beyond the scope of this study, the high-
mcc, USCG – 9/14/09
Appendix [[3]] – Comments upon MGN 328 – Operational Guidance
Regarding Table 1: The high-speed Masters in the peer review team did not find this tabular presentation user-friendly in the wheelhouse. One opined that some type of “slide rule” (such as the Weems and Plath speed/time/distance wheel) would be helpful, noting that some simple, visual presentation of vessel speed/relative sea direction/wave height might further enhance quick recognition and understanding. That said, the high-speed Masters have, since its publication, made good use of MGN 328(M) in combination with MCA Information Film: “High Speed Craft – Control in Following Seas” to raise their companies' awareness and to train other high-speed Masters. They understand MCA's concerns regarding copyright but consider the Information Film one of the best training tools currently available and suggest that MCA revisit the limited distribution rule with the objective of modifying the current DVD so that it may be given the widest possible unrestricted distribution.
Regarding Table 1: The high-speed Masters in the peer review team did not
mcc, USCG – 9/14/09
Appendix [[3]] – Comments upon MGN 328 – Operational Guidance
Regarding Figure 1 and Table 2: Several of the high-speed Masters in the peer review team found Table 2 the more user-friendly presentation. These Masters confirmed that the numbers presented for coastal wave speeds associated with significant wave heights are in fact representative of their experience. One high-speed Master noted that among the hardest concepts to grasp when operating a high speed catamaran are those of wave height, wave speed and wave period and their combinations that can occur . Table 2 is useful for relating wave height and speed. Another high-speed Master in the peer review team further confirmed the need to be aware of wave period as well as wave speed. Based on a postbow dive casualty analysis in 1999, his company’s high-speed Masters are trained to time the period between wave peaks regularly when underway. Their analysis concluded that regardless of other factors such as wave speed and height, a five-second wave period equates to a wave length of approximately 40 meters, which is generally the size (waterline length) of the high-speed catamarans in that company’s fleet. The 1999 analysis cited Maritime Safety Committee Circular 707: “IMO Guidance to the Master for Avoiding Dangerous Situations in Following and Quartering Seas” dated 19 October 1995, which indicates that wave period can be measured by stopwatch. This is a quick and easy way for high-speed Masters to know when they must take corrective action, especially when operating at speed down-sea.
Regarding Figure 1 and Table 2: Several of the high-speed Masters in the
mcc, USCG – 9/14/09
Appendix [[3]] – Comments upon MGN 328 – Operational Guidance
However, wave period is not addressed in the text of MGN 328 (M) or in figure 1 or Table 2. In order to include wave period in this discussion, the figure to the right shows the relationship between wave length, speed and period in the open ocean. An operator can use a stopwatch to estimate the wave period, then enter the figure on the lefthand side with that value and read the wave speed on the right or the wave length on the bottom. Knowing his boat length and speed relative to the length and speed of the waves, he can then decide whether to speed up or slow down or change course to avoid a potential problem. It is important to note, however, that this can change in coastal waters. As the water depth decreases, wave length and speed both decrease (and wave height increases). Wave period can vary somewhat, up or down, from the open ocean case. In fact, other high-speed Masters in the peer review team indicated that in their operational experience, factors such as water depth and current also influence wave formation, with the inference that wave behavior may be more complex than Figure 1 and Tables 1 and 2 would suggest, thereby giving users misleading information.
This table corresponds with the preceding figure. Start on the top line with the wave period, then read wave speed and length directly below.
mcc, USCG – 9/14/09
