Reversing The Boat

[Andrewcook]

When to coming to Moor we some time put the Engine in Revers to slowing it down but some on Boats Reversing is not so powerful enough as to going forward why not?

[grendel]

the shape of the propellor is designed to maximise power thrust in one direction, as such in reverse it may not be as powerful, also the front of a boat is generally pointy, so splits the water ahead, and the back of the boat flat, so trying to push the water behind the boat, which reduces the amout of reverse speed.

[Cal]

It very much depends on the boat and the set up.

 

The cruiser we had with duo props reversed very well, so well in fact that you had to watch for water coming over the bathing platform at times!

 

Broads hire boats with their flat sterns and single props just don't reverse so well and will also suffer from prop walk which pulls the stern to one side. 

[NeilB]

Another issue is most hire boats have restricted rpm to prevent them from going too fast, but this also reduces the power available in reverse.  Whenever possible we used a bracket behind the dash or simply moved the lever on the splines so it hit the dashboard to restrict rpm in forward but allow full power in reverse.

You can unscrew the **** for a modest increase or take the correct size allen key to move the lever on the splines, but that would be naughty!  

 

[oldgregg]

26 minutes ago, NeilB said:

You can unscrew the **** for a modest increase or take the correct size allen key to move the lever on the splines, but that would be naughty!  

I used to take the block off on dayboats pretty regularly or have the engine hatch up and adjust the throttle cable travel... You'd get a bit more power but it was rarely worth it.

Having said that, when we hired Santa Christina back in 1985 it was a different story. A lot of their market was for boats going to Ireland and so the two Norfolk boats had also had the Perkins 4.236 fitted (probably in case they didn't let well) and a wooden block was fitted in front of the throttles to stop people being mischievous.

Sadly, the wooden block was involved in an incident with a screwdriver and the boat seemed to go a LOT faster for the rest of the week... 

Those were the days. You really didn't need a bow thruster with that sort of power and a hull like that. The replacement Santa Christina (same build but not the same boat) that was on hire in the 90's also had the big Perkins and handling was awesome.

[annv]

Hi Andrew it's a power to weight ratio heavier boats need more power to stop than lighter ones plus tidel flow will have a effect, if you compared the acceleration of a car to a lorry lorry has more power but heavier. also a prop has a paddle wheel effect in reverse as the water is denser below the prop than it is above the prop thats why boats tend to go in a circle if helm is straight ahead John

[Vaughan]

There is a thread in the technical section called "The kick of the propellor" where we discussed this a couple of years ago. You may find a lot of the answers there.

[NeilB]

For some reason the swear filter does not like ****, as in doorknob!  I obviously have no idea for any other use of the word... 

[oldgregg]

I remember a few years back we discovered that it didn't like references to the initials of the Volkswagen Audi Group.

There was a thread where someone was talking about a TDI engine and the word in question was - you might say - 'snatched' from them.