I have a 17 ft. flat bottom skiff and a 17 ft. mako that i would like to tow behind my 31 (not at the same time). I was wondering if anyone had any experience... any special rigging? how fast? etc. I wanted to pull one of the smaller boats across the pamlico sound in NC (about 30 miles and sometimes a little choppy) for inshore fishing.
Thanks,
Bill
PS. Saw a boat out of MD named the Reel Lady? A dark blue sport fisherman with a tower that had been redone and enclosed. looked like it was heading to FL. Tied up overnight in Morehead City, NC. Couldn't find the skipper anywhere around and it was gone a daybreak the following day. Great looking boat whoever the owner may be.
Advice on towing?
Moderators: CaptPatrick, mike ohlstein, Bruce
Bill,
Two points that you have probably already considered: 1) rig a towing harness that attaches to both aft cleats that provides a center connection to the tow line itself (to keep the towed boat in the center of your wake); and chafing gear where the lines pass through the hause holes. 2) beef up the backing support to the wenching/towing eye on the bow of the boat. I've done the Pamlico Sound crossing many times, and you are right.....it can get as rough as anywhere I've seen. If the towing eye gets yanked out of your skiff during the tow due to rough seas (or due to a weak hull), the eye becomes a missle headed right back at you!
Two points that you have probably already considered: 1) rig a towing harness that attaches to both aft cleats that provides a center connection to the tow line itself (to keep the towed boat in the center of your wake); and chafing gear where the lines pass through the hause holes. 2) beef up the backing support to the wenching/towing eye on the bow of the boat. I've done the Pamlico Sound crossing many times, and you are right.....it can get as rough as anywhere I've seen. If the towing eye gets yanked out of your skiff during the tow due to rough seas (or due to a weak hull), the eye becomes a missle headed right back at you!
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Capt.Frank
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i guess you can go as fast as the smaller boat being towed could stand the sea conditions under its own power?
Would you just tie the tow rope to the center point of the rope between the two back cleats on the bertram? those old ski ropes had the pully than ran on the rope between the two tie points at the back of the boat. I have a 6x8x1/4 in. aluminum plate backing the eye on the skiff. haven't figured out how to reinforced the mako yet.
Would you just tie the tow rope to the center point of the rope between the two back cleats on the bertram? those old ski ropes had the pully than ran on the rope between the two tie points at the back of the boat. I have a 6x8x1/4 in. aluminum plate backing the eye on the skiff. haven't figured out how to reinforced the mako yet.
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CaptPatrick
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Towing may seem like a simple task, but there are some key points that must be taken into consideration. Some that the average boater isn't aware of...
First, dedicated tow boats, (ski boats do qualify as tow boats), have the Samson Post, from which the towed vessel, (or skier), is attached, centered on the keel line and forward of the rudders, out drives, or outboard engines. They also, except for ski boats, have a large horizontal tow bar at the transom that allows the tow line to move from side to side, but within a limited span.
This is necessary to maintain complete steering control of the towing vessel. The closer the point of attachment is to the rudders of the towing vessel, the less steering control the towing vessel has. (If you have those pesky little postage stamp stock rudders and gas engines, you're in for real difficulty...)
Second, all tows should only be done with braided or tight twist polypropylene line. Polypropylene has less stretch and will not snap back like nylon line will when it breaks. Polypropylene also floats and is less likely to fowl props and underwater gear when free in the water. For towing, I would not consider less than 1" polypropylene line.
Third, the towed vessel will be both dead weight and significantly greater drag. That equates to added stress on the towing vessel's engines. Depending on the amount of power and torque available to the towing vessel, the towed vessel can add enough drag to overtax the towing vessel's power by multiples.
Fourth, it will be virtually impossible for the average pleasure vessel to tow another pleasure vessel at much more than about 1/2 it's normal cruise speed for the sea conditions.
Fifth, there is a difference between a static load, (constant load), and a dynamic load, (momentary load). On flat calm water, no wind or current, the weight and drag of the towed vessel represent a nearly static load. Wave action, wind, current, and other factors create dynamic loads that can exceed the static load by multiples. Towing at 15 kt, a 1,000 lb static load in a moderate chop, with a 15 kt head wind, can easily develop well over 10.000 lbs of dynamic load to the entire towing components. The faster the towing vessel is making way, the higher the forces are multiplied. The strength of the towing vessel is only as strong as the weakest link.
So rigging a center point bridle towing line on a B31 to a 17' shallow draft boat is the only practical way to get the job done, but be very aware of the points above and proceed with caution. Each towed vessel will have it's own towing characteristics. If the towed vessel has rudders, secure the at amidships. If outboard or outdrive, the drive or motor should be in the down position and secured amidships. Failure to do so will allow the tow to wander.
Find a comfortable towing speed for the conditions and adjust the tow line to be a safe distance behind the towing vessel. With a fixed bridle, adjustments will be difficult. Better would be a two part bridle. The actual bridle that attaches to the tow vessel will have a center loop with a thimble. The tow line will be fastened, but adjustable, to the thimble. This way the distance can be adjusted from the towing vessel without having to adjust the length at the towed vessel.
For those wondering, yes, I have a USCG towing endorsement and have worked numerous commercial tows. Even if it was while mating on Noah's Arc...
First, dedicated tow boats, (ski boats do qualify as tow boats), have the Samson Post, from which the towed vessel, (or skier), is attached, centered on the keel line and forward of the rudders, out drives, or outboard engines. They also, except for ski boats, have a large horizontal tow bar at the transom that allows the tow line to move from side to side, but within a limited span.
This is necessary to maintain complete steering control of the towing vessel. The closer the point of attachment is to the rudders of the towing vessel, the less steering control the towing vessel has. (If you have those pesky little postage stamp stock rudders and gas engines, you're in for real difficulty...)
Second, all tows should only be done with braided or tight twist polypropylene line. Polypropylene has less stretch and will not snap back like nylon line will when it breaks. Polypropylene also floats and is less likely to fowl props and underwater gear when free in the water. For towing, I would not consider less than 1" polypropylene line.
Third, the towed vessel will be both dead weight and significantly greater drag. That equates to added stress on the towing vessel's engines. Depending on the amount of power and torque available to the towing vessel, the towed vessel can add enough drag to overtax the towing vessel's power by multiples.
Fourth, it will be virtually impossible for the average pleasure vessel to tow another pleasure vessel at much more than about 1/2 it's normal cruise speed for the sea conditions.
Fifth, there is a difference between a static load, (constant load), and a dynamic load, (momentary load). On flat calm water, no wind or current, the weight and drag of the towed vessel represent a nearly static load. Wave action, wind, current, and other factors create dynamic loads that can exceed the static load by multiples. Towing at 15 kt, a 1,000 lb static load in a moderate chop, with a 15 kt head wind, can easily develop well over 10.000 lbs of dynamic load to the entire towing components. The faster the towing vessel is making way, the higher the forces are multiplied. The strength of the towing vessel is only as strong as the weakest link.
So rigging a center point bridle towing line on a B31 to a 17' shallow draft boat is the only practical way to get the job done, but be very aware of the points above and proceed with caution. Each towed vessel will have it's own towing characteristics. If the towed vessel has rudders, secure the at amidships. If outboard or outdrive, the drive or motor should be in the down position and secured amidships. Failure to do so will allow the tow to wander.
Find a comfortable towing speed for the conditions and adjust the tow line to be a safe distance behind the towing vessel. With a fixed bridle, adjustments will be difficult. Better would be a two part bridle. The actual bridle that attaches to the tow vessel will have a center loop with a thimble. The tow line will be fastened, but adjustable, to the thimble. This way the distance can be adjusted from the towing vessel without having to adjust the length at the towed vessel.
For those wondering, yes, I have a USCG towing endorsement and have worked numerous commercial tows. Even if it was while mating on Noah's Arc...
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In Memory Walter K
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CaptPatrick
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As usual, it's the pros on this Board that offer the most in-depth responses. Thanks, Patrick, for covering those important points. The only point that I've practiced differently, is that I've towed a small center console with the outboard motor tilted up to about 45 degress to provide some rudder without the drag of the lower unit being all the way down. It is important to note that the boat had hydrolic steering, so once it was set midship it held that position.
thanks capt.
I have oversized rudders so hopefully that will not be an issue. how far back should the towed boat be? I think i will make a bridle with a thimble.
I do think i will probably limit to fairly calm and relatively short distance river towing in light of the speed constraints and concerns you mentioned. great info... thanks again and thanks to you also Tommy.
Bill Blount
I have oversized rudders so hopefully that will not be an issue. how far back should the towed boat be? I think i will make a bridle with a thimble.
I do think i will probably limit to fairly calm and relatively short distance river towing in light of the speed constraints and concerns you mentioned. great info... thanks again and thanks to you also Tommy.
Bill Blount
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CaptPatrick
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Bill,
The B31 starts to plane at 13 kt and creates a distinctive "V" pattern as the two prop washes converge. Your tow should be about 10 ft aft of that point, putting it in flat water. Depending on sea conditions, there will be a series of swells beyond that point too. Position the bow of the tow to be riding just aft of the first or second swell.
The tow must be close enough to the vessel towing to be in flat water, but not so far back as to allow the tow to wander across the first chine wake of the towing vessel. Again, each towed vessel can respond differently, so just keep adjusting the bridle and tow line to find the sweet spot.
Here's a diagram of the setup:
Start by securing the stbd bridle line to the stern cleat, allowing about 10 ft of line between the cleat and thimble. This leg of the bridle will remain fixed throughout the rest of the adjustments.
Next cleat the port leg of the bridle and adjust the length of that leg so that it pulls the thimble way off center to the post side.
Now, thread the tow line through the starboard chaffing gear and trough the thimble. Pay out about 20 ft and attach to the tow. Cleat it off on the stbd stern cleat, over the bridle leg.
Begin your tow and bring your speed up to about 7 kt. Slack off of the port bridle leg until the thimble and tow are centered behind your vessel and secure there.
Slowly bring up your speed to around 15 kt. Pay out the tow line until the tow is positioned aft of the converging prop wash and, if present, just aft of the first swell.
Slowly bring up your speed to the desired cruising speed, carefully monitoring how the tow is reacting to the increasing speed.
Re-adjust as necessary, but drop back to 7 kt or less to make any adjustments. DO NOT try to adjust at full towing speed.
Seizing the bridle:
Your bridle will be one length of line, approximately 30' long. Place the thimble in the center and tie it securly in place with sail twine or other small stuff. Now, using 3/8" braided nylon line, seize the two legs of the bridle together for a length of 12". Be sure that the seizing is tight to the thimble.
Begin by streching a couple of feet of the bridle tightly between two fixed points, at about waist high. Secure the thimble so that it won't turn during the seizing application.
Tape the tag end of the seizing line to the bridle legs at the opposite end from the thimble. Draw it to the thimble and tape it to the legs.
Run the seizing line through the thimble and double it back, bending a half hitch around the bridle legs & just behind the thimble. Now tightly wrap the line around the legs continuously, back away from the thimble, for a distance of 12". All of the turns must be as tight as possible and lay firmly next to one another.
complete the sizing, similar to the way you would complete a Bimini Twist, with a series of half hitches. A half hitch over one leg, then a half hitch over the other leg, followed with several half hitches over both legs together.
Cut the excess seizing line, melt back the ends, and tape off with electrical tape.
By the way, sections of old fire hose make excelent chaffing gaurds. Stich on some terrycloth for even softer surfaces. Keep 'em clean. Beach sand and paint don't get along...
Have fun and good luck.
The B31 starts to plane at 13 kt and creates a distinctive "V" pattern as the two prop washes converge. Your tow should be about 10 ft aft of that point, putting it in flat water. Depending on sea conditions, there will be a series of swells beyond that point too. Position the bow of the tow to be riding just aft of the first or second swell.
The tow must be close enough to the vessel towing to be in flat water, but not so far back as to allow the tow to wander across the first chine wake of the towing vessel. Again, each towed vessel can respond differently, so just keep adjusting the bridle and tow line to find the sweet spot.
Here's a diagram of the setup:
Start by securing the stbd bridle line to the stern cleat, allowing about 10 ft of line between the cleat and thimble. This leg of the bridle will remain fixed throughout the rest of the adjustments.
Next cleat the port leg of the bridle and adjust the length of that leg so that it pulls the thimble way off center to the post side.
Now, thread the tow line through the starboard chaffing gear and trough the thimble. Pay out about 20 ft and attach to the tow. Cleat it off on the stbd stern cleat, over the bridle leg.
Begin your tow and bring your speed up to about 7 kt. Slack off of the port bridle leg until the thimble and tow are centered behind your vessel and secure there.
Slowly bring up your speed to around 15 kt. Pay out the tow line until the tow is positioned aft of the converging prop wash and, if present, just aft of the first swell.
Slowly bring up your speed to the desired cruising speed, carefully monitoring how the tow is reacting to the increasing speed.
Re-adjust as necessary, but drop back to 7 kt or less to make any adjustments. DO NOT try to adjust at full towing speed.
Seizing the bridle:
Your bridle will be one length of line, approximately 30' long. Place the thimble in the center and tie it securly in place with sail twine or other small stuff. Now, using 3/8" braided nylon line, seize the two legs of the bridle together for a length of 12". Be sure that the seizing is tight to the thimble.
Begin by streching a couple of feet of the bridle tightly between two fixed points, at about waist high. Secure the thimble so that it won't turn during the seizing application.
Tape the tag end of the seizing line to the bridle legs at the opposite end from the thimble. Draw it to the thimble and tape it to the legs.
Run the seizing line through the thimble and double it back, bending a half hitch around the bridle legs & just behind the thimble. Now tightly wrap the line around the legs continuously, back away from the thimble, for a distance of 12". All of the turns must be as tight as possible and lay firmly next to one another.
complete the sizing, similar to the way you would complete a Bimini Twist, with a series of half hitches. A half hitch over one leg, then a half hitch over the other leg, followed with several half hitches over both legs together.
Cut the excess seizing line, melt back the ends, and tape off with electrical tape.
By the way, sections of old fire hose make excelent chaffing gaurds. Stich on some terrycloth for even softer surfaces. Keep 'em clean. Beach sand and paint don't get along...
Have fun and good luck.
One thing to check.
Many of the stern cleats I've seen and removed on 31's use #12 or possibly #14 screws into a wood block. Many times that block is cracked or decayed.
While in normal stationary tie up at the dock this will suffice even in some wind.
But the tow load can create quit the force on those screws. Check and make sure your stern cleats and the wood blocks they are affixed to are secured firmly.
BTW on all my north/south trips I've never seen the sound anything but a nasty piece of water.
Many of the stern cleats I've seen and removed on 31's use #12 or possibly #14 screws into a wood block. Many times that block is cracked or decayed.
While in normal stationary tie up at the dock this will suffice even in some wind.
But the tow load can create quit the force on those screws. Check and make sure your stern cleats and the wood blocks they are affixed to are secured firmly.
BTW on all my north/south trips I've never seen the sound anything but a nasty piece of water.
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CaptPatrick
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Not saying you should, but you certainly could...I have a 17 ft. flat bottom skiff and a 17 ft. mako that i would like to tow behind my 31 (not at the same time).
It's called a Christmas Tree Tow. Rather than using a centered bridle, you tow each boat directly off of one cleat and at staggered distances.
Last edited by CaptPatrick on Nov 13th, '10, 15:21, edited 1 time in total.
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CaptPatrick
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