CA1188934A - Modification on a rudder for boats and ships - Google Patents
Modification on a rudder for boats and shipsInfo
- Publication number
- CA1188934A CA1188934A CA000357746A CA357746A CA1188934A CA 1188934 A CA1188934 A CA 1188934A CA 000357746 A CA000357746 A CA 000357746A CA 357746 A CA357746 A CA 357746A CA 1188934 A CA1188934 A CA 1188934A
- Authority
- CA
- Canada
- Prior art keywords
- channel
- rudder
- boat
- plane
- propeller
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Abstract
ABSTRACT OF THE DISCLOSURE
The modification of a rudder for boats and ships, comprising a channel or tunnel disposed rearwardly of the screw which is rotatable about a substantially vertical axis. The channel has a closed, circular cross-sectional configuration. Two V-shaped notches are provided in the rearward end of the channel, the V-tips lying in the central vertical plane through the channel, such that on each side of this plane, a curved tongue is formed.
The front edge of the channel is spaced from the propeller plane so as not to intersect the propeller plane in any rudder position and the two curved tongues are immovable relative to one another. In one embodiment, the channel is arranged in combination with a conventional plate-shaped rudder, one half-section of the channel being arranged on each side of the rudder.
The modification of a rudder for boats and ships, comprising a channel or tunnel disposed rearwardly of the screw which is rotatable about a substantially vertical axis. The channel has a closed, circular cross-sectional configuration. Two V-shaped notches are provided in the rearward end of the channel, the V-tips lying in the central vertical plane through the channel, such that on each side of this plane, a curved tongue is formed.
The front edge of the channel is spaced from the propeller plane so as not to intersect the propeller plane in any rudder position and the two curved tongues are immovable relative to one another. In one embodiment, the channel is arranged in combination with a conventional plate-shaped rudder, one half-section of the channel being arranged on each side of the rudder.
Description
~8~3~34 The present invention relates to a modi~ication on a rudder for boats and ships~ com-prising plates disposed on both sides of the rudder and parallel with the rudder sur~aces. Many boats have poor steering capabilities, especially at slow speeds. This is particularly true for small boats, such as the Norwegian "snekke" (a 16- to 24-foot open fishing boat, pointed at both ends, most oEten clinker built), and for other types of boats having a relatively deep bottom, a long keel and driven by an inboard motor, where the propeller turns about the same axis at all times and thus cannot participate in the steering. Such boats have especially poor steering capabilities when reversing. In fact, some boats do not answer the helm at all when reversing at slow speeds. Some other boats can answer the helm when reversing by turning only in the one direction.
It is obvious that this deficiency presents great problems in situations in which precise manoevering is required, for example, when sailing out of or into a harbor or in other situations where it is necessary to steer the ~raft while reversing. The problems with such boats can be so grea-t that the owner of the boat simply cannot risk taking his boat out of harbor if the winds and sea are blowing toward land.
'~
~"33~
The effect of a boat rudder is to deflect the flow of water relative to the longitudinal direction of the boat whether this flow results from the speed of the boat or from water which has been set in motion by the screw. The propeller flow, however, is far from laminar, and it therefore has a rela-tively bad effect on the steering of -the boat. Therefore, a boat travelling at slow speed will have poorer steering than the same boat travelling at higher speeds. In some cases, the screw will reduce the steering properties of the boat. This is particularly true when reversing, because the laminar flow of water which moves along the hull of the boat wil~ be broken up by the prope]ler, which has poor screw properties when reversing, the blades cf a propeller being con-stru~ted first and foremost with forward propulsion in mind. On boats which have poor steering capabilities in reverse, thereforer one must often set the boat in motion backwards and then cut out the propeller before the rudder will have any steering effect.
Several different types of aids have been tried in attempts to improve the steering properties of boats of the above type. Thus, various '-ypes of : guide plates on both sides of the rudder surface have been tried.
A modification on a rudder is known from Norwegian patent No. 59~795, in which plates tha-t are parallel with the rudder surface are provided on each side of -the rudder, the leading edge of -the pla-tes projecting forward of the middle leading edge of -the rudder. The primary object of this modification is to balance the rudder, in -that one thereby obtains steering surfaces which lie in fron-t of the rudder shaft. A similar modification is ]~nown from ~.S.
pa-tent No. 3,181,492.
It is known from U.S. pa-tent No. 2,328,04]. to mount arch-shaped guide wings on both sides of a conven-tional plate rudder in such a manner -tha-t the guide wings are disposed radially exterior of the propeller when -the rudder is in the neutral position.
However, the modi.fications of -this type known hitherto have not had the desired effect, and at present no effective aid exis-ts for increasing or improving the steering capabilities, especially when reversing, on boats : of the type defined above.
The presen-t invention is to provide for the modi-fication of a rudder for boa-ts and ships which comprises plates di.sposed on both sides `
3~
of the rudder and parallel with the rudder surfaces which improves the steering properties of the boat both when rev-ersing and during forward propulsion.
~ccording to the present invention there is pro-vided in a rudder arrangement for boats and ships, compris-ing a channel of substantially circular cross-section which is disposed rearwardly and coaxially of the propeller and which is rotatable about a substantially vertical axis, the walls of said channel at the rearward end thereof being pro-vided with two V-shaped notches with the respective apices of the notches lying on a central vertical plane extending through the channel so as to form an arched tongue on both sides of said plane, the improvement in which the front edge of said channel is spaced from the propeller plane so as not to intersect said plane in any rudder position, and the two arched tongues are immovable relative to one another and extend parallel to one another both on forward motion and reversing motion of the boat or ship, in which reversing motion the mo-tor propeller of the boat or ship is in reverse rotation, so as to provide increased steering capabilities for the boat or ship, both on said forward and reversing motion.
Numerous trials have been shown that this configura-tion of a channel-shaped rudder provides quite superior steer-ing properties, especially when reversing. This is very important, as reversing with boats have a pointed bottom configuration, such as the Norwegian "snekke" fishing boat, has always been problematic. With a rudder having the con-figuration defined above, such a boat will answer the helm equally well in both directions, while it 3~
would normally answer the helm only in the direction of rotation for the propeller. The steering properties of the boat will also be improved in the forward direction, especially when moving forward at very slow speeds.
According to a preferred embodimen-t of the inven-tion -the tongues constitute approximately one-half of the total length of the channel in the longitudinal direction of the boat.
A special embodiment of -the invention is charac terized in that the channel is arranged in combination with a plate-type rudder, the channel being arranyed symmetri-cally on both sides of the rudder plate. Such an arrange-ment will be practical for a boa-t which is equipped with a conventional plate rudder, as it permits one to attach a half-sec-tion of the channel on each side of the rudder.
The invention will be elucida-ted further in the following with reference to the accompanying drawings, which illustrate two different embodiments of the invention.
Figure 1 shows a first embodiment of a rudder according to the inven-tion, mounted on a small boat, in perspective, and , .
3~
Figure 2 shows the same embodiment seen directly from ~bove.
Figure 3 shows a second embodiment of the rudder according to the invention, in perspective, a~d Figu,res 4 and 5 show the embodiment of Figure 3 seen straight from the back and directly from above, respectively.
In accordance with the embodiment illustrated in Figure 1, a circular, channel-shape~d rudder 1 i5 provided between the stern 2 of the boat and a lower rudder support 3. The rearwardly-pro~ecting support 3 is -the most common construction on small boats, but one also finds types of boats in which this support is not present, in which case the rudder is supported solely by the rudder post ~.
The boat illustrated in this example is driven by a three-blade screw with reversible directions of rotation. The rudder shaft 4 is attached to the channel 1 forwar~ of the middle of the total length L of the channel. Two V-shaped notches have been cut into the ~ at its rearward end, the -tip~of each V lying in the central vertical plane through the channel 1. In this manner, respective arch-shaped 3~
tongl1es 7,8 are formed on each slde of said plane, the total length a of the tongues in the longitudinal direction of the channel being approximately equal to one-half the -total length L of the channel.
Figure 3 shows an embodiment which is well suited for rebuilding the rudder of a boat which is already equipped with a conventional plate rudder 9, placed between the stern 2 of the boat and the lower support 3. In this example, also the boat is driven by a three-blade screw 5 with reversible directions of rotation. The rudder is rotated by means of a rudder shaft 4, which is placed a distance behind the leading edge of the ruddex plate 9 in order to obtain a certain balancing effect.
Attached to both flat sides of the rudder 9 are arched guide plates 11 and 12. The curvature of the plates is in accordance with a circular line in the crosswise direction of the boat, such that the two plates 11,12 together form a circular~shaped channel. The lateral marginal edges 13 of the plates 11,12 ~Figure 5) are parallel with one another and with the rudder surface on the plate rudder 9.
The plates 11 and 12 are attached at their upper and 1ower edges 14 and 15 to the respective upper and 3~
lower edges oE the rudder surface. The forward edge on the plates 11,12 is disposed somewhat astern of the rudder shaft 4. The plates 11,12 have a ~8 curved rearward edge 'n~, such that the outer marginal edges 13 of the plate project somewhat astern of the plate parts, which are attached to the rudder at 14 and 15. In this way, tongues or overhangs 17 are formed~
The diameter of the channel which is formed by the two plates 11 and 12 is larger than the screw diameter of the propeller 5. In regard to the dimensions of the plates 11 and 12, the length a of the o~erhang 17 is approximately equal to the remaining length h of the total length L (see Figure 5) t i.e., the length a of the overhang 17 is approximately equal to one-half of the total length of the plates 11 or 12. The ratio of the length L (=a ~ b~ to the diameter lies between 3~4 and 3:6.
A rudder modification in accordance with the exemplified embodiments was tested on a small fishing boat which had extremely poor steering properties, especially when reversing. At slow speeds, this "snekke" boat did not answer the helm 3~
at all in one direction during a reversing operation.
The boat's berth was situated such that the sea and wind often blew toward land, and it often happenea that the owner could not take his boat out for the sole reason that it was not sufficiently manoeverable, as it was impossible to steer the boat in reverse.
After the modification according to the invention was installed, the owner claimed that the boat was as easy to steer as an automobile, and that it answered the helm when driven in reverse both at slow speeds and at full speed. In addition, the turn radius during forward propulsion had also become substantially smaller.
Another effect of the modification according to the invention is that it also prevents or greatly reduces the downward drag on the stern end of boats of this type. This is a common phenomenon, and it reduces speed or increases fuel consumption rather significantly. In order to preven-t this, some boats have a hull built with an expensive support plane or support fins in the region of the screw. Such hull modifications can be rendered un-necessary with the use of the invention, and the price of the hull correspondingly reduced.
It is obvious that this deficiency presents great problems in situations in which precise manoevering is required, for example, when sailing out of or into a harbor or in other situations where it is necessary to steer the ~raft while reversing. The problems with such boats can be so grea-t that the owner of the boat simply cannot risk taking his boat out of harbor if the winds and sea are blowing toward land.
'~
~"33~
The effect of a boat rudder is to deflect the flow of water relative to the longitudinal direction of the boat whether this flow results from the speed of the boat or from water which has been set in motion by the screw. The propeller flow, however, is far from laminar, and it therefore has a rela-tively bad effect on the steering of -the boat. Therefore, a boat travelling at slow speed will have poorer steering than the same boat travelling at higher speeds. In some cases, the screw will reduce the steering properties of the boat. This is particularly true when reversing, because the laminar flow of water which moves along the hull of the boat wil~ be broken up by the prope]ler, which has poor screw properties when reversing, the blades cf a propeller being con-stru~ted first and foremost with forward propulsion in mind. On boats which have poor steering capabilities in reverse, thereforer one must often set the boat in motion backwards and then cut out the propeller before the rudder will have any steering effect.
Several different types of aids have been tried in attempts to improve the steering properties of boats of the above type. Thus, various '-ypes of : guide plates on both sides of the rudder surface have been tried.
A modification on a rudder is known from Norwegian patent No. 59~795, in which plates tha-t are parallel with the rudder surface are provided on each side of -the rudder, the leading edge of -the pla-tes projecting forward of the middle leading edge of -the rudder. The primary object of this modification is to balance the rudder, in -that one thereby obtains steering surfaces which lie in fron-t of the rudder shaft. A similar modification is ]~nown from ~.S.
pa-tent No. 3,181,492.
It is known from U.S. pa-tent No. 2,328,04]. to mount arch-shaped guide wings on both sides of a conven-tional plate rudder in such a manner -tha-t the guide wings are disposed radially exterior of the propeller when -the rudder is in the neutral position.
However, the modi.fications of -this type known hitherto have not had the desired effect, and at present no effective aid exis-ts for increasing or improving the steering capabilities, especially when reversing, on boats : of the type defined above.
The presen-t invention is to provide for the modi-fication of a rudder for boa-ts and ships which comprises plates di.sposed on both sides `
3~
of the rudder and parallel with the rudder surfaces which improves the steering properties of the boat both when rev-ersing and during forward propulsion.
~ccording to the present invention there is pro-vided in a rudder arrangement for boats and ships, compris-ing a channel of substantially circular cross-section which is disposed rearwardly and coaxially of the propeller and which is rotatable about a substantially vertical axis, the walls of said channel at the rearward end thereof being pro-vided with two V-shaped notches with the respective apices of the notches lying on a central vertical plane extending through the channel so as to form an arched tongue on both sides of said plane, the improvement in which the front edge of said channel is spaced from the propeller plane so as not to intersect said plane in any rudder position, and the two arched tongues are immovable relative to one another and extend parallel to one another both on forward motion and reversing motion of the boat or ship, in which reversing motion the mo-tor propeller of the boat or ship is in reverse rotation, so as to provide increased steering capabilities for the boat or ship, both on said forward and reversing motion.
Numerous trials have been shown that this configura-tion of a channel-shaped rudder provides quite superior steer-ing properties, especially when reversing. This is very important, as reversing with boats have a pointed bottom configuration, such as the Norwegian "snekke" fishing boat, has always been problematic. With a rudder having the con-figuration defined above, such a boat will answer the helm equally well in both directions, while it 3~
would normally answer the helm only in the direction of rotation for the propeller. The steering properties of the boat will also be improved in the forward direction, especially when moving forward at very slow speeds.
According to a preferred embodimen-t of the inven-tion -the tongues constitute approximately one-half of the total length of the channel in the longitudinal direction of the boat.
A special embodiment of -the invention is charac terized in that the channel is arranged in combination with a plate-type rudder, the channel being arranyed symmetri-cally on both sides of the rudder plate. Such an arrange-ment will be practical for a boa-t which is equipped with a conventional plate rudder, as it permits one to attach a half-sec-tion of the channel on each side of the rudder.
The invention will be elucida-ted further in the following with reference to the accompanying drawings, which illustrate two different embodiments of the invention.
Figure 1 shows a first embodiment of a rudder according to the inven-tion, mounted on a small boat, in perspective, and , .
3~
Figure 2 shows the same embodiment seen directly from ~bove.
Figure 3 shows a second embodiment of the rudder according to the invention, in perspective, a~d Figu,res 4 and 5 show the embodiment of Figure 3 seen straight from the back and directly from above, respectively.
In accordance with the embodiment illustrated in Figure 1, a circular, channel-shape~d rudder 1 i5 provided between the stern 2 of the boat and a lower rudder support 3. The rearwardly-pro~ecting support 3 is -the most common construction on small boats, but one also finds types of boats in which this support is not present, in which case the rudder is supported solely by the rudder post ~.
The boat illustrated in this example is driven by a three-blade screw with reversible directions of rotation. The rudder shaft 4 is attached to the channel 1 forwar~ of the middle of the total length L of the channel. Two V-shaped notches have been cut into the ~ at its rearward end, the -tip~of each V lying in the central vertical plane through the channel 1. In this manner, respective arch-shaped 3~
tongl1es 7,8 are formed on each slde of said plane, the total length a of the tongues in the longitudinal direction of the channel being approximately equal to one-half the -total length L of the channel.
Figure 3 shows an embodiment which is well suited for rebuilding the rudder of a boat which is already equipped with a conventional plate rudder 9, placed between the stern 2 of the boat and the lower support 3. In this example, also the boat is driven by a three-blade screw 5 with reversible directions of rotation. The rudder is rotated by means of a rudder shaft 4, which is placed a distance behind the leading edge of the ruddex plate 9 in order to obtain a certain balancing effect.
Attached to both flat sides of the rudder 9 are arched guide plates 11 and 12. The curvature of the plates is in accordance with a circular line in the crosswise direction of the boat, such that the two plates 11,12 together form a circular~shaped channel. The lateral marginal edges 13 of the plates 11,12 ~Figure 5) are parallel with one another and with the rudder surface on the plate rudder 9.
The plates 11 and 12 are attached at their upper and 1ower edges 14 and 15 to the respective upper and 3~
lower edges oE the rudder surface. The forward edge on the plates 11,12 is disposed somewhat astern of the rudder shaft 4. The plates 11,12 have a ~8 curved rearward edge 'n~, such that the outer marginal edges 13 of the plate project somewhat astern of the plate parts, which are attached to the rudder at 14 and 15. In this way, tongues or overhangs 17 are formed~
The diameter of the channel which is formed by the two plates 11 and 12 is larger than the screw diameter of the propeller 5. In regard to the dimensions of the plates 11 and 12, the length a of the o~erhang 17 is approximately equal to the remaining length h of the total length L (see Figure 5) t i.e., the length a of the overhang 17 is approximately equal to one-half of the total length of the plates 11 or 12. The ratio of the length L (=a ~ b~ to the diameter lies between 3~4 and 3:6.
A rudder modification in accordance with the exemplified embodiments was tested on a small fishing boat which had extremely poor steering properties, especially when reversing. At slow speeds, this "snekke" boat did not answer the helm 3~
at all in one direction during a reversing operation.
The boat's berth was situated such that the sea and wind often blew toward land, and it often happenea that the owner could not take his boat out for the sole reason that it was not sufficiently manoeverable, as it was impossible to steer the boat in reverse.
After the modification according to the invention was installed, the owner claimed that the boat was as easy to steer as an automobile, and that it answered the helm when driven in reverse both at slow speeds and at full speed. In addition, the turn radius during forward propulsion had also become substantially smaller.
Another effect of the modification according to the invention is that it also prevents or greatly reduces the downward drag on the stern end of boats of this type. This is a common phenomenon, and it reduces speed or increases fuel consumption rather significantly. In order to preven-t this, some boats have a hull built with an expensive support plane or support fins in the region of the screw. Such hull modifications can be rendered un-necessary with the use of the invention, and the price of the hull correspondingly reduced.
Claims (4)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a rudder arrangement for boats and ships, comprising a channel of substantially circular cross-section which is disposed rearwardly and coaxially of the propeller and which is rotatable about a substantially vertical axis, the walls of said channel at the rearward end thereof being provided with two V-shaped notches with the respective apices of the notches lying on a central vertical plane extending through the channel so as to form an arched tongue on both sides of said plane, the improvement in which the front edge of said channel is spaced from the propeller plane so as not to intersect said plane in any rudder position, and the two arched tongues are immovable relative to one another and extend parallel to one another both on forward motion and reversing motion of the boat or ship, in which reversing motion the motor propeller of the boat or ship is in reverse rotation, so as to provide increased steering capabilities for the boat or ship, both on said forward and reversing motion.
2. A rudder arrangement according to claim 1, in which the tongues constitute approximately one-half of the total length of the channel in the longitudinal direction.
3. A rudder arrangement according to claim 1 or 2, in which the ratio of the total length of the channel to the diameter of the channel lies between 3:4 and 3:6.
4. A rudder according to claim 1 or 2, in which the channel is in combination with a conventional plate-shaped rudder, one-half of the channel being disposed on each side of the rudder plate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000357746A CA1188934A (en) | 1980-08-07 | 1980-08-07 | Modification on a rudder for boats and ships |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000357746A CA1188934A (en) | 1980-08-07 | 1980-08-07 | Modification on a rudder for boats and ships |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1188934A true CA1188934A (en) | 1985-06-18 |
Family
ID=4117584
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000357746A Expired CA1188934A (en) | 1980-08-07 | 1980-08-07 | Modification on a rudder for boats and ships |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1188934A (en) |
-
1980
- 1980-08-07 CA CA000357746A patent/CA1188934A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |