MacGregorSailors.com

Hello
If I have to tow a on its trailer out of the water on a ramp with a rope: What will be the load on the roap?

Thanks - kurz

I don't know the answer here, but please tell the back story... why do you need to tow it out with a rope?

I would think something stronger than 3000Kg would be needed if you have ballast in, given the boat with ballast would be around 2200Kg (5000lbs) plus the trailer at around 500Kg (1100lbs)

kurz wrote:Hello
If I have to tow a on its trailer out of the water on a ramp with a rope: What will be the load on the roap?

Thanks - kurz

How steep is the ramp

Seriously don't use rope use a proper snatch strap rated at least for 2000kg heck 8000kg ones are only $50 so get one that is way overkill if that sucker breaks under load it is the whip of death. .

Recommended slopes for boat ramps is between 12-15%. At the high end, it would be about 8-1/2 degrees slope. For a 5000 lb [2273 kg] boat/trailer combo and 15% slope, and with zero rolling resistance, it would take about 740 lb [336 kg] pull to hold or roll it at constant speed (holding is a constant speed of zero ).

Add in 10% rolling resistance (could be higher), or 495 lb [225 kg] and you get 1235 lb [561 kg]. Theoretical. Actual rolling resistance may be higher, and I'm guessing at boat/trailer weight. And you still have to accelerate the load from a standing stop, which adds load to the strap.

Many tow straps I saw online have questionable ratings. They seem to suggest the weight of the vehicle you can tow on flat ground (my interpretation). Others have a minimum breaking strength, which is more meaningful, like this one https://www.amazon.com/gp/product/B01H5 ... i=15737581 but it's over $50 US. The $11 US straps with the 10,000 lb [4546 kg] ratings sound fishy to me. https://www.amazon.com/gp/product/B011A ... i=15737581 and I'm guessing that's some sort of meaningless towed vehicle weight figure or something.

And as kadet correctly points out, they're big rubber bands, and may do a lot of damage if broken from overload. Kevlar is stiffer than steel rope, but crazy expensive, and wire rope is still stretchy, so that danger is there no matter what you use. Even chain is stretchy.

Another thing cheaper in OZ, only $49.95 what is happening here?

https://www.4wdsupacentre.com.au/hercul ... AkKR8P8HAQ

Hercules - 8000kg Snatch Strap
Specifications
Minimum Breaking Strength: 8,000kg
Stretch Factor: Up to 20%
Width: 60mm
Length: 9m
Colour: White
Sleeve colour: Black