Reply
 
Thread Tools Search this Thread
 
Old 16 November 2011, 18:50   #11
Member
 
Country: UK - England
Town: Colchester
Length: no boat
Join Date: Aug 2011
Posts: 12
Quote:
Originally Posted by boristhebold View Post
It looks very odd, maybe a stupid question but there isn't some form of hardware still attached that should be used only when the boat and engine is being towed by a car? Something about the lower leg looks strange as in what is that big hunk of metal attached. Lower legs should be streamlined but yours looks the opposite and that appears to be where the water is shooting up from. Perhaps you could take a pic with the engine raised while out of the water so we can see lower leg.
Wow - thank you for all the responses so far. Much appreciated!

The boat isn't stored at home, but I took a couple of photos of the outboard when I got it which I have just put up at https://picasaweb.google.com/1043743...42706542699698.

Not a stupid question at all as it does look a bit weird, but I am pretty sure that the lump of metal is supposed to be there. Will have a look in the instruction manual tomorrow to make sure I haven't made a real schoolboy error.

I would tend to agree that it looks as though it is too low, but the cavitation plate is pretty much skimming the surface of the water once on the plane (which I thought was about right) and it definitely goes a lot better with the motor sitting straight on the transom and it cavitates (I think? - you can feel the power slipping but the revs surge) a LOT more when I lifted the motor. Any higher and I think it will lose all power and barely move.

If I did lift it to stop the spray problem, are there propellors which would cope better with being at the surface of the water? There is plenty of water coming out of the cooling system, so I think it can handle being higher, but the lack of power and constant cavitation was frustrating.

There is also the slight problem of the clamps being off the top of the transom if it goes much higher. I want to bolt the motor on, but only once I am confident that the height is right. When I use the decking plank, I was really worried about the clamps popping off as they were very high.

Any other theories?

Thanks again to everyone - I am really grateful.
__________________

__________________
JoeF1974 is offline   Reply With Quote
Old 16 November 2011, 19:12   #12
Member
 
Sea Witch's Avatar
 
Country: Ireland
Town: clifden
Make: Fletcher Bravo Arrow
Length: 5m +
Engine: Yamaha 175
Join Date: Jan 2010
Posts: 43
R u racing urs or leisure use . Ur picture is showing an aluminum prop on , u need to get ur hands on a ss prop wit good cups on it pre 15 pitch for chop/flat or 13 pitch if ur out in the surf . Aluminum prop don't grip dat well at speed in d corners on cats.ie zapcat , ceaser , aqarius or Gemini hulls .
__________________

__________________
Sea Witch is offline   Reply With Quote
Old 16 November 2011, 19:38   #13
Member
 
Country: USA
Town: Seattle
Boat name: Water Dog
Make: Polaris
Length: 4m +
Engine: Yamaha 60hp
Join Date: Apr 2007
Posts: 1,152
Your picasa album doesn't work for me here in the States.
But in your video, near the beginning where you say "raised 1.5cm" the outboard is still too low there. The metal blobby bits are supposed to be on your lower unit, the whole thing is just still too low.

I would guess your 30hp did not come with the correct prop to run that cat really fast. That's why it ventilating (drawing too much air in from the surface). As Sea witch says you need a cupped prop which may be hard to find in smaller sizes for a 30hp.
__________________
captnjack is offline   Reply With Quote
Old 17 November 2011, 03:43   #14
Member
 
Country: UK - England
Town: Colchester
Length: no boat
Join Date: Aug 2011
Posts: 12
Quote:
Originally Posted by captnjack View Post
Your picasa album doesn't work for me here in the States.
But in your video, near the beginning where you say "raised 1.5cm" the outboard is still too low there. The metal blobby bits are supposed to be on your lower unit, the whole thing is just still too low.

I would guess your 30hp did not come with the correct prop to run that cat really fast. That's why it ventilating (drawing too much air in from the surface). As Sea witch says you need a cupped prop which may be hard to find in smaller sizes for a 30hp.
Sorry - I did check the link but think it worked as I was logged in. I think https://plus.google.com/u/0/photos/1...42703085227489 should work?

I think you are right that the propellor is not working for the boat. I have no idea what a 'cupped prop' really means but will have a search and see what I can find out. I have come across various phrases such as cleaver / chopper / bunny, all of which mean next to nothing to me but I am sure the answers are out there.

Thanks again for the help. If anyone has any views on how to source a new prop, then I am all ears.

Cheers,
Joe
__________________
JoeF1974 is offline   Reply With Quote
Old 17 November 2011, 12:24   #15
Member
 
Country: UK - England
Town: Colchester
Length: no boat
Join Date: Aug 2011
Posts: 12
Hmmm - not as easy as I had hoped, although I have got my head round the various types of propeller available.

Any advice / thoughts on where to source decent SS props in the UK?

Thanks
Joe
__________________
JoeF1974 is offline   Reply With Quote
Old 17 November 2011, 12:43   #16
Member
 
Country: USA
Town: oregon
Make: zodiac
Length: 3m +
Engine: M40C
Join Date: Sep 2011
Posts: 70
I would suggest that you leave the motor height as you have it for best performance. Now you still have the water gushing problems. So..., fabricate a "water spray shield" out of pieces of pvc material, or aluminum plate, or whatever to attach on the transom on either side of the motor to deflect the majority of water back. The would be triangular in shape. If you make it out of pvc fabric it could attach partially with snaps to be folded back to facilitate in removing/attaching the motor.

Some sib's are made with these shields from the manufacturer.

The problem is your boat rides so high on the water when on plane that to raise it up to prevent the slow speed water-gushing problem you have cavitation issues, as you found out.

This would be cheaper than buying new props to experience with, if that is an issue. Otherwise, raising the engine and trying different props will probably fix the issue rather than just fixing the symptom.
__________________
sinner is offline   Reply With Quote
Old 17 November 2011, 13:29   #17
Member
 
Country: USA
Town: Seattle
Boat name: Water Dog
Make: Polaris
Length: 4m +
Engine: Yamaha 60hp
Join Date: Apr 2007
Posts: 1,152
Ok that link worked. Maybe a dumb question but is that the correct shaft length for the boat? Looks like it might be 20inches. Aka a long shaft
__________________
captnjack is offline   Reply With Quote
Old 17 November 2011, 13:31   #18
Member
 
Country: UK - England
Town: Colchester
Length: no boat
Join Date: Aug 2011
Posts: 12
Hi Sinner,

Thanks for the advice. I have seen a few splash guards on similar boats, so had thought about that.

I do, however, like your comment:

Quote:
Originally Posted by sinner View Post
Otherwise, raising the engine and trying different props will probably fix the issue rather than just fixing the symptom.
In the ideal world, it would be good to get the height right and still have the performance.

Thinking about it more today, the boat is a lot lighter to drive and easier to steer with the motor a bit higher. Whilst it is incredibly direct when at the lowest setting, it somehow feels a bit too grippy and there must be a lot more drag. You certainly feel it on your arm and the boat was veering off to the right a bit. I think you could fix that with the little tab, but I am tempted to try a different prop to see if that can achieve a magical balance.

I don't mind getting a bit wet and am still loving it but am now addicted to getting the most out of it in terms of speed. Will sink a bit of money into right prop if that will help.

Thanks again,
Joe
__________________
JoeF1974 is offline   Reply With Quote
Old 17 November 2011, 13:37   #19
Member
 
Country: UK - England
Town: Colchester
Length: no boat
Join Date: Aug 2011
Posts: 12
Quote:
Originally Posted by captnjack View Post
Ok that link worked. Maybe a dumb question but is that the correct shaft length for the boat? Looks like it might be 20inches. Aka a long shaft
Not a dumb question at all but I am 99.9% sure that it is a short shaft as all the documentation says that it is and it was sold as a short shaft (I got it 2nd hand, albeit hardly used).

The manual is in my car so am going to double check this evening and have a look for the propellor specification, but I may go and physically measure it to make sure tomorrow (boat stored about 15mins from work).

Thanks
Joe
__________________
JoeF1974 is offline   Reply With Quote
Old 17 November 2011, 14:17   #20
Member
 
Sea Witch's Avatar
 
Country: Ireland
Town: clifden
Make: Fletcher Bravo Arrow
Length: 5m +
Engine: Yamaha 175
Join Date: Jan 2010
Posts: 43

Name:   image-694355727.png
Views: 236
Size:  47.1 KB

Dis wat there used for !!!!!
Attached Thumbnails
Click image for larger version

Name:	image-263646436.jpg
Views:	77
Size:	58.6 KB
ID:	63925   Click image for larger version

Name:	image-3663383993.jpg
Views:	73
Size:	55.3 KB
ID:	63926  
__________________

__________________
Sea Witch is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 03:31.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.