Reply With QuoteIf I made a false bottom on the pod to match the exact shape of the bottom of the boat hull, then dropped the motors to suit, would this fix it?
Effectively then what I have done is extended the hull.
Cheers
Pete
G'day BM,
I think you may be right with the pressure wave theory.
The props are 17-K Yamaha props.
These little 5m cats were never made in sterndrive configuration - only ever twin outboards.
All the first of the 500 series were outboard wells, and the last model made had pods.
Noosacat actually still makes this exact hull now ... it has either twins on pods or a single centremounted engine (merc 90 with hi 5 prop)
According to the formula, the motors are set at the right height.
Are the cupped props a Yamaha item, or are they made by others (like Solas)
Cheers
Pete
If I made a false bottom on the pod to match the exact shape of the bottom of the boat hull, then dropped the motors to suit, would this fix it?
Effectively then what I have done is extended the hull.
Cheers
Pete
My mate said to me yesterday when we were following a boat in traffic that its sad when you can identify a brand and model only by looking at the transomG'day Fishingrod,
Mate I think you could spot a cat anywhere
I love cats. Except I cant tow one ! I was looking for a 5m second hand cat or Hydrofoil, Hookem, Maxicat etc but they are pretty border line with my 1600kg tow capacity.
Ive never seen that boat in real life. It has been advertised for sale some time in the last 12 months. Thats where I got the photo from. (pinched it off the advert)The boat lives at Redcliffe ... is the owners name Geoff?? I cant remember.
Its a nice little toy you got there. Hope you have some fun over summer. A simple fix might be to stay below 4500rpm
If Yam dont have one as a listed part any other manufacturer will be able to provide them. Or get yours cupped.
If you extend the hull bottom right through then that should work well. Drop the engines back to normal height (since its now effectively the same as a normal transom mounted engine) and see how it fares.
Cheers
Yeah, the one I'm referring to had too much weight on the back and too much nose up attitude.Originally Posted by Grand_Marlin
G'day Gelsec,
Absolutely no help at all, but an interesting story #
I have to go the opposite and get the nose up a bit more.
When I trim the motors up, I start to get cavitation before I get any trim angle.
Cheers
Pete
You can see that the problem is reversed, your's looks too light, or the pods might be too big and too low, giving the stern too much floation. So maybe the solution is reversed.
I agree with the bottom shape of the pods looking too square, someone was acting out their design theories by the look of it.
Add ballast to the pods, problem solved
merry xmas
Steve
Add ballast to the pods, problem solved #
Steve
... and I suppose you suggested ballast is 2 healthy blokes standing down the back of the cat holding Tiagra 50w's??
Cheers
Pete
A simple fix might be to stay below 4500rpm #
Sorry, not an option
Cheers
Pete
Thanks BM, I will give Colin at Performance Propellors a call and see what he can do.
Cheers
Pete
I have also sent an email / pics to Noosacat, but they are rarely much help.
Cheers
Pete
GM,
Height in theory is ok, Pod design is questionable and it doesn't surprise me that they have some issues, from just looking at it!
The Pod on the Green cat is more the design/style of what one would expect. Similar to this one which works extremelly well and has no issues with pressure waves or the like but the clearance is quite different and so is the sponson shape. So is the angle of the engine mount?
dunno? but from the rake of the pods the motors are still too vertical or is this just an illusion from the pic?If I made a false bottom on the pod to match the exact shape of the bottom of the boat hull, then dropped the motors to suit, would this fix it?
One of the things with NC's, there's been quite a bit of playing around gone on over the years?
Regards, Kerry.
Quiet finga
about the 25 -(30) tohatsu any resolution?
How much space have you got between the cat hull and the pod? if its more then 25 mm then you creating soda water you have to fill the gap and increase your pod transom slope min 15 degrees in
The rule still applies-- level of hull to outboard leg should stand 90 degrees each outboard already is made to accomodate 15 degrees incline, so if the transom is standing 90 degrees? the outboard is looking outward thus some cavitation.
This will be a small project for marlin after hollidays , in the meantime have a good xmas and lots of fishing cheers Ahoj
Yes that will stop the soda water and you have a smoother power and better ride
G'day All,
Thanks for you ideas and help.
I got the Yamaha props cupped.
Colin at performance propellors did the job.
He said the standard prop didnt have enough cup in it anyway ... so with a bit of blacksmith work, the props were done.
And...
Worked perfectly ... just as I wanted and very happy with the result.
It has dropped the max revs from 5500 to 5300, but the top speed has gone up by 4 knots !
Footnotes:
As suggested Noosacat were a pack of unhelpful pricks
the pods are standard noosacat pods and they are the same design as what appears on the 2300 walkaround, which is the current model
Cheers, and thanks very much again,
Pete
[quote author=Grand_Marlin link=1166349316/15#28 date=11672
As suggested Noosacat were a pack of unhelpful pricks
Bruce harris went in for a visit one day when he was in the area and was promptly kicked out,you think they would have at least shown him around the factory and offered him a cup of tea!
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