Towing - effect on fuel consumption?

ready123 · Post by **ready123** » Tue Jan 13, 2009 10:02 am

Anyone here tow their dinghy/tender?
I'm interested in the ill effects on fuel consumption. I have heard comments on real bad to not much difference... when compared to a davit on the swim platform setup.

I'm planning to upgrade in size and will not be putting it on my davits.

Right now I have a Walker Bay Genesis 10' RIB with 20 HP Yamaha on Hurley Davits on my swim platform and am thinking about moving to a Whaler 130 Super Sport with 40 HP Mercury.

The extra weight off the back of the transom is a no go for me... so am planning to tow the Whaler..... not a major concern as normal usage is not in rough weather. Use on Great Lakes only; though the lake chop can often be worse than ocean as the waves can be short and high by comparison.
On a bad day I guess the crew will have to man the tender.

Interested in hearing any experiences with towing something like a Whaler....

prowlersfish · Post by **prowlersfish** » Tue Jan 13, 2009 1:13 pm

I do not think it would make much difrence as long as the whaler is not plowing thru the water you are talking about towing at low speed not on plane correct ?

wowzer52 · Post by **wowzer52** » Tue Jan 13, 2009 1:57 pm

Last summer I towed three waverunners in a row behind my F-32 for about ten miles every weekend at 8 knots and didn't notice any difference in fuel consumption but the hard part was adjusting the rope length so they rode in the trough of the wake. Too far foreward and they pulled hard on the rope and I could feel the extra drag and too far back and they would surf on the face of the next wake and be out of control. People said with the yellow jet skis we looked like a mother duck and her three babies. Quack..or is that peep, peep.

ready123 · Post by **ready123** » Tue Jan 13, 2009 5:50 pm

prowlersfish wrote:I do not think it would make much difrence as long as the whaler is not plowing thru the water you are talking about towing at low speed not on plane correct ?

Actually I am not... I'm planning to tow at around 18 knots... maybe less if by moving weight off my platform allows me to run slower than 3,200 rpm while on plane. I'm hoping that by towing rather than platform mounting I will in fact gain a slower plane speed. With dinghy on the back I have to get her up to 3200 rpm which is about 19 mph on GPS. Much slower than that and she wants to start to plow.

Can be done, here is one at about 20 knots

MattSC · Post by **MattSC** » Tue Jan 13, 2009 6:38 pm

Make sure that your backing plate on your cleats is up to snuff, that will put alot of stress on them. Also I would recommend using a towing bridle to help distribute the load. I tow an 11' rib with 15hp outboard and don't really notice a difference, but I usually tow it around 8 kts or so. I did tow a guy at night with a 25' cruiser about 15 miles from LI Sound all the way up the Housatonic river. It was new boat too, his first trip! Even with the towing bridle it did effect the handling, though I'm sure it shouldn't be as bad with a whaler.

ready123 · Post by **ready123** » Tue Jan 13, 2009 7:23 pm

MattSC wrote:Make sure that your backing plate on your cleats is up to snuff, that will put alot of stress on them. Also I would recommend using a towing bridle to help distribute the load.

Backing plate is 1/8" Ally plate rectangle.

On the whaler discussion forum http://continuouswave.com/whaler/
some use bridles, some use from cleat to cleat via the bowring (works like a bridle) as in the photo I posted, some use two lines from bowring... all with good results. Some guys even run with the engines down which I would not do.
One interesting thing I picked up on was trolling a 12' chain from the whaler's stern eye to keep it's bow up to keep drag low.

I'm comfortable with how to do it... was mainly interested to see if anyone had experienced what my theoretical expectation is: that towing correctly is no worse than the davit mount load on the swim platform which alters the boats planing attitude and causes the aft end to sit lower.