Spray from outboard?

Flyguy · 28 June 2009, 22:52

I'm using my zodiac 3.4 and Tohatsu 9.8hp weekly and love it. However I can't find the correct trim setting for the outboard. Every time I go on plane and open it up I get loads of engine spray over the transom so I have to back off? I've even fitted Doel Fins which didn't help. It's currently set for the 2nd lowest trim setting.
Any advise?

m chappelow · 28 June 2009, 23:08

Quote:

Originally Posted by Flyguy

I'm using my zodiac 3.4 and Tohatsu 9.8hp weekly and love it. However I can't find the correct trim setting for the outboard. Every time I go on plane and open it up I get loads of engine spray over the transom so I have to back off? I've even fitted Doel Fins which didn't help. It's currently set for the 2nd lowest trim setting.
Any advise?

i use a long shaft on my 3.4 sib as i use the same engine on a heavy displacement fishing boat ,so i get a bit of spray when i use it on my sib ,but i put a shaped block of wood in the flat on the leg ,theres a photo of it on a couple of threads on here , held on with cable ties which sorts my spray problem ,how about a piece of thick rubber to go around the leg as a sheild to stop spray,i had doel fins on too which slowed me down ,most boats i have had seem to want the lowest trim setting .

Flyguy · 28 June 2009, 23:19

That's a good. Can you please post a link to the pic so I get an idea of how you have done it.
Thanks again.
John

m chappelow · 28 June 2009, 23:41

Quote:

Originally Posted by Flyguy

That's a good. Can you please post a link to the pic so I get an idea of how you have done it.
Thanks again.
John

couple of pics as requested ,

Mosseriser · 28 June 2009, 23:58

Oooh, another long shaft engine user on a short shaft transom !

do you get any problems with the boat pitching up on full throttle ?, or any other problems other than spray with a long shaft engine ?

the reason i ask, is that i have bought myself a Avon Rover 3.1m airdeck SIB and i already had a Yamaha 8hp longshaft 2stroke engine left over from my big boat days many years ago

Do you think i should build up the transom to make the anti cav plate the same height as the bottom of the transom?, or should i stop fussing over it and just put it on and get boating ?, I intend to use in on estuaries and costal within a few hundred meters of the shoreline.

Just wondering what you think, as you run a long shaft engine on a short shaft transom

Thanks

m chappelow · 29 June 2009, 00:16

to be quite honest i dont see much difference with using a short or a long shaft on this boat though it is heavy ,except might loose a bit of speed couple of knots or so ,it never cavitates or airates even in lumpy seas so i never loose power ,and i have never had any bother with it pitching up though its not exactly a big engine ,.only thing is if i need to clear the prop of weed its an extra 5 inches to stretch out ,.

Flyguy · 29 June 2009, 12:59

Thanks for posting the pic. I will knck something up and let you know how I get on.
Cheers
John

Poly · 29 June 2009, 21:47

Flyguy - it might be worth searching for some threads by "Locozodiac" on here. He is a "SIB guy" based in S. America, who if I remember rightly had similar experiences. He got quite excited about two issues (1) making sure the boat is correctly inflated and (2) the engine height on the transom. I think he believed the latter was responsible for spray back over the transom.

Flyguy · 29 June 2009, 23:41

Found it! Excellent, thanks Polwart. I'll try this first as it is an easy experiment.
Cheers
John

m chappelow · 01 July 2009, 11:37

just as a matter of intrest i was invited to a local sailing club last night to see how a s.i.b my sib would compare with there hard dory safety boats, and i borrowed a 15 hp 2stroke short shaft for the evening to use on my 3.4 sib ,guess what 2 crew and no difference to speed handling except we had a bit of airiation now and again ,but most noticable was the large amount of spray kicking up ,only good point was that with 5 adults on board went a bit faster than with my 8 hp 4stroke long shaft ,.

Flyguy · 21 July 2009, 08:56

Just as an update, I tried the outboard with a 2cm piece of wood under it on the transom and there is no spray at all! Works like a charm even at full tilt.

Thanks to everyone for the advice. Amazing a 2cm height adjustment can make such a difference?

I guess I just have to remember to jam the wood under the engine each time I launch?

Thanks
John

BumbleAbout · 21 July 2009, 12:23

Or you could zip tie the spacer wood to the outboard or even screw it into the top of the transom (usual caveats apply re use Skiaflex & marine stainless steel screws) ...

Goinfishin · 21 July 2009, 15:01

Hi Flyguy I have a zodiac 3.50s and have the same problem with spray over the transom at full tilt, any chance of posting a link to the transom height thread.

Thanks Brian.

Flyguy · 21 July 2009, 21:58

Here you go:

http://www.rib.net/forum/showthread....ighlight=spray

Nick Honey · 19 August 2011, 15:57

I'm new to all of this so can I just check that everyone is agreeing that you CAN run a long shaft on a SIB? I need a longshaft as the spare engine on my 23' Clinker ferry boat. But I also have a couple of SIBs for the kids to zoom around in. One is a 2.6XM - planning to use a 10hp longshaft, the other is a Quickslilver 3.4 Airdeck with a 15hp longshaft.

So is everyone agreeing I can do that, but either increase the transom height and/or be ready to get some spray??

This seems a better bet than getting a shortshaft and then fixing one of those hinged brackets to get the engine low enough on the back of my main boat?

All comments/advice most welcome and appreciated.

Cheers. Nick

catabisis · 19 August 2011, 16:24

What is the rubber thing on your transome?

m chappelow · 19 August 2011, 21:11

Quote:

Originally Posted by catabisis

What is the rubber thing on your transome?

One of the two drain trunks ,
if on the move takes about a good min or so to empty the boat if its full from a dumping wave .

catabisis · 19 August 2011, 22:54

Quote:

Originally Posted by m chappelow

One of the two drain trunks ,
if on the move takes about a good min or so to empty the boat if its full from a dumping wave .

Would you mind explaining a bit more about them? I am new to inflatables. Sorry about the ignorance. Why would you need the tube coming off the transome instead of just having the hole there? It there a "door" attached to the hole which allows the water to escape, but not enter from the outside-sort of like a scupper? What is the purpose of the metal rod attached? Thanks for your time.

willk · 19 August 2011, 23:08

They are an open scupper (but below the waterline, so really just a HOLE) with a flexible hose on the outside. The rods are actually taut cords which are used to pull the hoses upright above the water level.

They are thus watertight at rest but can be rapidly deployed while underway to passively dump huge volumes of water in seconds.

You know you want a pair

catabisis · 20 August 2011, 02:45

Quote:

Originally Posted by willk

They are an open scupper (but below the waterline, so really just a HOLE) with a flexible hose on the outside. The rods are actually taut cords which are used to pull the hoses upright above the water level.

They are thus watertight at rest but can be rapidly deployed while underway to passively dump huge volumes of water in seconds.

You know you want a pair

I certainly do want them, if it makes boating safer. I will look into it. However, I don't think I will be banging away on rough days. Not on Lake Erie anyway. Now, if I were back living on the Chesapeake Bay, maybe. Thanks for taking the time to answer. I like the way you have the compartments in the fore on the tubes. It is another thing I will look into to doing. Where did you get them?