Towing with a RIB

[damianham]

If I had to tow a 12 ton boat across 200nm of open sea in calm weather would a large RIB be up to the job - with say a 200 HP outboard ?

[letsgetsailing3]

That would seem to be, you know, not the best option.

It would require a lot of time, a lot of gas, and doesn't really play to the strengths of the craft.

[a64pilot]

Seeing as how seatow does it day in and out I'd say yes
OK not 200 miles but other than fuel and time what's the difference between 20 and 200?


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[Vasco]

Originally Posted by a64pilot

Seeing as how seatow does it day in and out I'd say yes
OK not 200 miles but other than fuel and time what's the difference between 20 and 200?


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Weather!! A 200 mile tow will take at least 24 hours. Lots of time for weather to kick up.

[a64pilot]

He's the one that said calm sea, not me. I think 24 hours may even be a little optimistic, that's over 8 kts, I'd plan on a day and a half, leave at first light, take maybe as much as 180 gl of fuel? Probably be limited to the RIB's hull speed.
There are times that you can be pretty sure of good wx for over 24 hours.
I'm assuming this tow might be where there are currents, like Gulf stream maybe if so that can effect things.

On edit, Bangkok Thailand, ain't the Gulf stream

[letsgetsailing3]

Again, I think you have to look at it in terms of best options.

[jannw]

not a great idea for such a long distance, but you would probably want to tie up the RIB fore and aft against the side of the boat rather than tow it with a line from ahead. That way it becomes an extension of the boat being towed.

Or you could just remove the 200hp outboard motor and mount in on a bracket on the back of your boat ;-)

[44'cruisingcat]

I've been involved with towing 2 mono's, a 40 footer and a 50 footer using two RIBS tied alongside, with 15 and 18 hp. We managed around 3-4 knots not thrashing the outboards. But we only went a few miles each time.

200 miles would be feasible, but you'd need very good weather.

[Stumble]

Technically possible sure, recommended not really.

Figuring a towing speed of 4kn you are looking at 50 hours across. Even good weather offshore is going to have swells, and weather forcasting that far out is pretty inexact. Not to mention that most outboard boats won't have near the fuel necessary or a hard point strong enough to handle realistic loads.

Frankly this is one of those things that if you went with experienced people who really knew what they were doing you might be ok, but the likelihood of catastrophic failure is very high.

As for two arrangement...

Towing behind is prefered for open water towing since it is more efficient, has less drag, and reduced inclination to veer. But it costs a lot in maneuverability. The longer the tow rope the less control, but also the more shock absorption in the line. Balancing these is important.

Towing alongside gives the greates control over where the boat is going, but reduced efficiency, and has higher loads on the hard points.

[Cheechako]

You need a properly located tow post (Midships -ish), otherwise, tie the RIB alongside and it will work.

[a64pilot]

I've towed pretty big and heavy things, 45' Sportfisherman for a few miles in 3' seas with my 21' Center Console and 175 hp outboard by towing from the two transom mounted hooks and 100' 5/8" line. I have a bridle that has a pulley that spreads the load on both eyes. I think we were making about 5 kts and I think fuel burn was around 5 an hour? Full throttle was 22 an hour and trolling was about 1.5 I think for comparison

I wouldn't want to be tied alongside and the longer the tow line, the better it felt. I think if I had the proper pitch prop it would have cut the fuel burn quite a lot.

[a64pilot]

Originally Posted by Cheechako

You need a properly located tow post (Midships -ish), otherwise, tie the RIB alongside and it will work.

SeaTow, Boat US all have tow posts, never seen one on anything else except a ski boat though, of course that wouldn't work

[Cheechako]

I have tried to tow sailboats and a trawler with 10ft RIB x 15hp. With t he tow rope attached to the stern (bridle) of the RIB it could not be done. The RIB just skates from side to side. Not sure how to do it. Maybe a bigger tow boat with more HP works. But if you want to tow your mothership with a small RIB, tie alongside and it works great.

[Geoff54]

Originally Posted by Cheechako

I have tried to tow sailboats and a trawler with 10ft RIB x 15hp. With t he tow rope attached to the stern (bridle) of the RIB it could not be done. The RIB just skates from side to side. Not sure how to do it.

15 hp is plenty to tow most sailboats up to about 50’ or so, for short distances in fairly flat water. If you were skating from side to side you weren’t towing sympathetically

The larger boat must do all the steering and the dingy must be kept in a completely straight line with the boat being towed. Apply the power slowly and if you start to skate, ease off, get back in line and then gently apply power again. Obviously you need to rig a bridle on the dingy and as far forward as you can – midships would be ideal but is not actually practical. Otherwise, as you said, rig for a hip tow - as long as there's room it's much easier. Either way, both people need to know what to do.

As for the original question: If there was no better option, I'd try to figure out a way to mount the outboard on the boat to be moved.

[Ozbullwinkle]

I have towed a 60 foot catamaran which weighs over 20 tons with a 3.5m RIB with a 25HP outboard for 12 miles in the open sea when the conditions were calm & we tied the RIB alongside. This worked fine but tied alongside in a chop would be a different story. In your case a RIB with a 200 HP outboard would be large enough to do a conventional tow with a long tow rope.