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Misty Blue · 05-05-2008, 02:14 PM

Dave M

Good thread! Here are a few, well more than a FEW, tips on towing...

First. Towing a boat is a dangerous operation. Sorry. Please don't look at me like that. It just is.

With the exceptions of someone is distress or a small boat for a short distance on a calm day it is better to leave it to the professionals, ie. Sea Tow or TowBoat/US. Some marinas are OK but most of their employees are not trained for towing. Your Ford dealer does not send a mechanic out to tow your car. AAA has the equipment and know how to do it without hurting anyone or the car.

Let's start with equipment.

CLEATS: Your boat. Many boats have cleats that are little more than jewelry. The cleats that you use should be large enough to handle the lines needed for the tow. They should be bolted through the hull/deck and have a metal backing plate below. Since you can't control the condition of the other boat you should use their cleats as a last option. If you can attach to his bow ring. West Marine has a cool tool called a "kicker hook" to make this job MUCH safer.

THE TOW ROPE (HAWSER): Sorry Silver Duck but I totally disagree with you on line stretch. You want and need the hawser to stretch. If there were no stretch in the line tremendous strains will be felt on the attachment points of both boats. I feel that the best line for small craft is double braided nylon. 1/2 to 3/4 inch would be OK. These lines will absorb the varying forces of the tow like a bungie cord. But beware, they will part (break) if stretched more than 40%.

Do not cleat the hawser down with a weather hitch. That requires two hands to untie and you may have to divorce the tow in a hurry. A knife should be handy to cut it as well.

There are three forces acting on the tow. Inertial, load and dynamic.

Inertial load is the force needed to overcome the first part of the tow, getting the boat up to speed. Once you are moving this goes away.

Load is the force needed to overcome the drag of the vessel. This is constant and will help determine the speed of the tow.

The last is dynamic and it is the one to watch. Dynamic load is developed by the differences in speed between the two boats. At sea it is usually caused by the boats being out of sync. That is when the tower is going up a swell and the tow is going down a swell the hawser slackens. Then when the tower is going down the next swell while the tow is going up the other the line pulls taught, bad. That is why we use nylon. It takes up some of this force. To avoid this situation we adjust the length of the hawser to be in sync. That is both boats going up and down at the same time. There are other tricks too.

On the Lake it is tougher because of a busy Saturday in the Weirs bay the three foot wakes coming from every direction take up the towing captain's attention. The best thing to do is to increase the hawser length to get a longer bungie cord and to increase the cantenary (dip) in the line but remember you are not marked as a tow vessel (lights etc.) and don't let someone go between you and the tow. There is a hawser there!

Towing speed. Did you ever think that you were ripped off by a cabbie taking the long way? People sometimes think that a tower is going slow to increase the bill but there is a mathematical formula that dictates maximum towing speed. You take the square root of the waterline length of the tow, multiply it by 1.2 and then multiply the product by the following quality factor(sailboat= 1.0, inboard boat=.9 and outdrive with drive down-.8)

Take a 25 foot (waterline length) I/O and you want to keep the drive down for steering etc.

Square root of 25 =5X1.2 = 6X.8 =5 knots maximum speed. Five knots, and that is in good conditions.

Seeker likes to use a procedure called a side tow. I've done many and a few on the Lake but am not a huge fan of it. It requires several very good fenders, good cleats on both boats and a well trained crew. Two is minimum, three is better. What's more I always worry about someone in the towed boatsticking their hands between the boats. Ouch!

These are just a few of the things that are considered for a tow. There are many more. Combine this knowledge with years of experiance and you can see why towing captains get paid to do it.

So Dave being the excelent and dedicated boater that I know you are I say go out and get a 100' 1/2" nylon line for a tow line whip the ends, no eyes. Make a bridle out of 3/4" three strand nylon splice in an eyes plice on either end. Chapman's has a good section on how to set it up. Use your own good judgment on if you want to takle the tow.

And PS. If you keep a battery jump pac on board for the Summer it will get used!

See ya at the Fest! Misty Blue.

05-05-2008, 02:14 PM	#9
Misty Blue Senior Member Join Date: Jul 2004 Posts: 658 Thanks: 121 Thanked 283 Times in 98 Posts	Towing tips. Dave M Good thread! Here are a few, well more than a FEW, tips on towing... First. Towing a boat is a dangerous operation. Sorry. Please don't look at me like that. It just is. With the exceptions of someone is distress or a small boat for a short distance on a calm day it is better to leave it to the professionals, ie. Sea Tow or TowBoat/US. Some marinas are OK but most of their employees are not trained for towing. Your Ford dealer does not send a mechanic out to tow your car. AAA has the equipment and know how to do it without hurting anyone or the car. Let's start with equipment. CLEATS: Your boat. Many boats have cleats that are little more than jewelry. The cleats that you use should be large enough to handle the lines needed for the tow. They should be bolted through the hull/deck and have a metal backing plate below. Since you can't control the condition of the other boat you should use their cleats as a last option. If you can attach to his bow ring. West Marine has a cool tool called a "kicker hook" to make this job MUCH safer. THE TOW ROPE (HAWSER): Sorry Silver Duck but I totally disagree with you on line stretch. You want and need the hawser to stretch. If there were no stretch in the line tremendous strains will be felt on the attachment points of both boats. I feel that the best line for small craft is double braided nylon. 1/2 to 3/4 inch would be OK. These lines will absorb the varying forces of the tow like a bungie cord. But beware, they will part (break) if stretched more than 40%. Do not cleat the hawser down with a weather hitch. That requires two hands to untie and you may have to divorce the tow in a hurry. A knife should be handy to cut it as well. There are three forces acting on the tow. Inertial, load and dynamic. Inertial load is the force needed to overcome the first part of the tow, getting the boat up to speed. Once you are moving this goes away. Load is the force needed to overcome the drag of the vessel. This is constant and will help determine the speed of the tow. The last is dynamic and it is the one to watch. Dynamic load is developed by the differences in speed between the two boats. At sea it is usually caused by the boats being out of sync. That is when the tower is going up a swell and the tow is going down a swell the hawser slackens. Then when the tower is going down the next swell while the tow is going up the other the line pulls taught, bad. That is why we use nylon. It takes up some of this force. To avoid this situation we adjust the length of the hawser to be in sync. That is both boats going up and down at the same time. There are other tricks too. On the Lake it is tougher because of a busy Saturday in the Weirs bay the three foot wakes coming from every direction take up the towing captain's attention. The best thing to do is to increase the hawser length to get a longer bungie cord and to increase the cantenary (dip) in the line but remember you are not marked as a tow vessel (lights etc.) and don't let someone go between you and the tow. There is a hawser there! Towing speed. Did you ever think that you were ripped off by a cabbie taking the long way? People sometimes think that a tower is going slow to increase the bill but there is a mathematical formula that dictates maximum towing speed. You take the square root of the waterline length of the tow, multiply it by 1.2 and then multiply the product by the following quality factor(sailboat= 1.0, inboard boat=.9 and outdrive with drive down-.8) Take a 25 foot (waterline length) I/O and you want to keep the drive down for steering etc. Square root of 25 =5X1.2 = 6X.8 =5 knots maximum speed. Five knots, and that is in good conditions. Seeker likes to use a procedure called a side tow. I've done many and a few on the Lake but am not a huge fan of it. It requires several very good fenders, good cleats on both boats and a well trained crew. Two is minimum, three is better. What's more I always worry about someone in the towed boatsticking their hands between the boats. Ouch! These are just a few of the things that are considered for a tow. There are many more. Combine this knowledge with years of experiance and you can see why towing captains get paid to do it. So Dave being the excelent and dedicated boater that I know you are I say go out and get a 100' 1/2" nylon line for a tow line whip the ends, no eyes. Make a bridle out of 3/4" three strand nylon splice in an eyes plice on either end. Chapman's has a good section on how to set it up. Use your own good judgment on if you want to takle the tow. And PS. If you keep a battery jump pac on board for the Summer it will get used! See ya at the Fest! Misty Blue.