Water at transom ?

Scotty · 22 December 2002, 22:00

Guy's, a little information needed please. I took out the rib today for a blast. The sea was quiet ( small swell) and stuff all wind. At around 3/4 throttle my rear passengers were getting a large amount of water sprayed up on them from the transom area. It was coming up between the transom and the engine like a shower. I slowed down and it made it better. Further on we had no swell at all and no spray at full speed. I had changed the trim very slightly and moved one of the kids forward to the bow. Any advice please..... two soaked and pissed off kids want to know if this happens all the time.

DJL · 22 December 2002, 22:30

Scotty,

I think this is due to the height of the engine on the transom.

My boat is suffering the same problem after I got my new engine. The engineers said that raising the engine would help, however they were a little worried that raising the engine and installing a higher pitched prop (engine is over revving at the moment) would increases my speed too much.

I'm going to give steel developments a call soon and see what they recommend.

Daniel

Scotty · 22 December 2002, 22:46

Quote:

Originally posted by DJL
Scotty,

I think this is due to the height of the engine on the transom.

My boat is suffering the same problem after I got my new engine. The engineers said that raising the engine would help,
Daniel

My thoughts as well but the engine has been on the boat for a year and the previous owner seemed to know a lot about powerboats. And the problem was gone later in the following sea.

DJL · 22 December 2002, 22:55

I only notice it when the sea is flat and you get a calm, interupted flow of water under the stern of the boat.

You can quickly rule out height problems but checking with a ruler but personnally if this is the first time you have noticed it I wouldn't worry too much about it.

Pete7 · 22 December 2002, 22:56

Try trimming the engine a bit first to see if a minor adjustment can solve it. Otherwise yep its the height that need changing.

As a start point the anti cavitation plate on the engine should be 1 inch above the bottom of the transom. If that works and everything is fine then it can be raised again, one hole at a time. However on a rib raising it to high will result in the prop ventilating in turns as the tubes can't be pressed down into the water they lift the stern enough for the prop to pull down air from the surface. This can be reduced by trimming the outboard in a little for sharp turns. Changing the engine height is quite straight forward on an outboard, just need a couple of friends and some spanners, takes about half an hour. Use a block of wood under the engine fin and the trailer jockey wheel to raise and lower the back of the boat as required.

Manos · 23 December 2002, 11:14

The RIB you talking about is the new Zodiac you've got I believe.
If it is, try to lower the engine down a wee bit (not trim it down). Most likely is that your engine is mounted too high on the transom.
As (if I remember rightly) you bought it 2nd hand possibly the previous owners wanted some more speed at the top end and the engine was mounted at a higher level than it should for a 'family friendly' run.
In any case the Zodiac importer in Greece is a friend of mine and will ask the question to him after the hols and let you know if you still haven't cured the problem.

Robert1 · 29 March 2004, 15:15

Sorry to dig this thread up again, but I had the same problem this weekend on my new 4.8

Scotty, did raising the engine solve the problem?
Thanks,

Robert

Scotty · 30 March 2004, 17:02

Quote:

Originally posted by Robert1
Sorry to dig this thread up again, but I had the same problem this weekend on my new 4.8

Scotty, did raising the engine solve the problem?
Thanks,

Robert

Rob,
I forgot I posted this and thought someone else was using my name

The problem is there some times but only at full speed ! The boat goes back into the water this week after a long wintr and I will tell you then.

Regards,

Luke.