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View Full Version : Cormorant's Idea works on permatrim



dreemon
21-11-2009, 04:23 PM
I tried Cormerant's theory of adding spacers between the cav plate and permatrim to get it higher out of the water and gain top speed that was lost when I fitted it,

I raised the perm plate up by 15 mm using brass tube ( fr the shed) and bought longer screws $ 5 the job took max 20 mins,

not a true test because I didn't do a thourogh job at keeping numbers, But today I took the boat out 4.7 glass cuddy with 90 2st yam, today my boat was heavier by about 70 kg than my normal and was getting a higher WOT speed :D 2 kph more, looking over the stern I can see that the permatrim is out of the water more, I only took a stab at how high I should go but think I jagged it,

still the same out of the hole but better crusing speed and gained a bit on rpm too, the only negitive it might have is not as slow a planing speed :-/ and that's only a maybe,

seems to have benifitted the boat by heaps and to easy and cheap not to do it, end result is fuel economy,

I hope someone else can do the same thing , just keep better numbers and post it. Cheers and Thanks Cormerant 8-)

FNQCairns
21-11-2009, 06:52 PM
Nice! It's in the pipeline for mine, I looked for the foil i had stored away but haven't found it yet, do you think yours is high enough to not cause any drag at your favourite cruise speed?

This will be the real worth of the Corm-foil-mod:)

cheers fnq

dreemon
21-11-2009, 07:08 PM
I think It's really close to were I want it but will need to try it with my typical load (family) I do have about 6 mm left of thread to raise it if needed, it's a great idea for fine tuning, today was mostly leaning over the back at WOT, will check the cruise speed next time out, Tomarrow? :D

my motor is up as high as it can go on hole pattern without drilling 4 more holes into the transom. so for my situation it's really helpfull,

howd your trailer go? I'll need to do bits of welding on mine soon. also what foil have you got?

FNQCairns
21-11-2009, 07:33 PM
Trailer is all back to legal like, I do have some minor rust to deal with next.

The one I have is a 200se I used it originally to get the hull over it's poor build until I felt confident enough in diagnosis to chop the offending bits off, then I packed it away somewhere.

Yeah it would be interesting to hear if you think your doing less RPM at whatever is your preferred cruise, its always a measurable amount between foil and no foil and often it can be enough to move up to an extra pitch prop.

My only real negative consideration is if some numbskull decides step on it when sitting up higher oh and the dunny plunger behaviour when at anchor.

cheers fnq

Jarrah Jack
21-11-2009, 08:34 PM
Do these things reduce the rock and roll at anchor much boys?

Cheers

FNQCairns
21-11-2009, 08:55 PM
Do these things reduce the rock and roll at anchor much boys?

Cheers


Not in my experience but they can calm the up and down somewhat.

cheers fnq

wiz
22-11-2009, 09:56 AM
After reading Comorant's idea it got me thinking, as I do feel that the foil SE 300 on my motor 50hp Honda does create drag at cruising speed.

1 If the antiventilation plate is out of the water at speed the what is the purpose of the pick up on the under side ???

2 By installing spacers between the foil and antivent plate are you going to place more stress on the bolts and antivent plate that may causes it to break

Cheers

Alchemy
22-11-2009, 10:10 AM
Dreemon,

Sounds like a good outcome. You may want to replace the brass tube spacers with aluminium as I suspect the brass will react with the aluminium of your outboard causing corrosion probs at some time.

Regards,
Dave.

dreemon
22-11-2009, 11:43 AM
Alchemy, thanks for the heads up on the brass and corrosion, was wondering if there might be a prob using it, when I take it for anouther run I'll see if the height is right for cruise speed then adjust with the alloy tube, I'll prob go up to 20 mm spacers,

wiz, q # 1 A; not sure :-/

Q # 2 I did think about that but don't think theres anymore pressure on the plate than if the foil is bolted onto the cav as it will be riding above the water most of the time from now on.

cheers

Roughasguts
22-11-2009, 12:38 PM
Why don't you raise the motor one bolt hole!

That will raise the foil out of the water around the right amount as well.
No need for spaces then.

Cheers

ozscott
22-11-2009, 12:55 PM
He might want the prop still as much in the water as now - I like the idea of spacing up the foil. Have you got tabs as well? I took my foil off stuck on tabs, but didnt try the 2 together.

Cheers

dreemon
22-11-2009, 01:24 PM
[quote=dreemon;1099797]
my motor is up as high as it can go on hole pattern without drilling 4 more holes into the transom. so for my situation it's really helpfull,

Rags , just dont want more holes and it's really close to where I want it so just using this method for a bit of adjustment


Ozscott , Dont have the tabs, if this works out for saving some fuel I'll be happy, still curious on how they would work on mine though.

Roughasguts
22-11-2009, 04:38 PM
[quote=dreemon;1099797]
my motor is up as high as it can go on hole pattern without drilling 4 more holes into the transom. so for my situation it's really helpfull,

Rags , just dont want more holes and it's really close to where I want it so just using this method for a bit of adjustment


Ozscott , Dont have the tabs, if this works out for saving some fuel I'll be happy, still curious on how they would work on mine though.

Mate you don't get more holes in your transom!! there already there on your motor 4 holes in the top bracket and a slide system on the bottom of the motor transom mount, go take a look.

But Ouch if it's already on the top hole then what a lousy set up in the first place ( go fix it ) it may as well be done properly as I suspect the holes already there aren't sealed properly, if there that slack in the set up!

It's easy to move your motor up one notch. If you wan't to know ask me!!!takes a few minutes to do!! might need some sealer and flow coat though!!!

Cheers.

Chimo
22-11-2009, 05:09 PM
Hi Ozscott

I added foils, one set on each motor, and later added trim tabs(lencos)

I noted approx 25 to 30 ml lift in the boat stern with the foils and also found the boat was throwing heaps less water after they went on. Advantage was less blown spray with strong side winds when cruising slow offshore.

When the tabs went on the foils stayed put. The tabs, even when in the fully up position added to what the foils had already given and aided an even quicker transition to planing from displacement. The boat bow does not rise as much during the transition if the tabs are tapped down a bit too.

Tabs as you know allow the Vag's bow to stay upright and so slice / enter waves without the nasty shoulder slap / bang when the boat's not level.

As you know my motors are lifted so at med to higher speed cruise the foils are clear of the water surface so it stills pulls 42+kns if you want to flush the carbies!

Why dont you throw the foils back on and see if they contribute?

Cheers
Chimo

dreemon
23-11-2009, 06:33 AM
[quote=dreemon;1100029]

Mate you don't get more holes in your transom!! there already there on your motor 4 holes in the top bracket and a slide system on the bottom of the motor transom mount, go take a look.

But Ouch if it's already on the top hole then what a lousy set up in the first place ( go fix it ) it may as well be done properly as I suspect the holes already there aren't sealed properly, if there that slack in the set up!

It's easy to move your motor up one notch. If you wan't to know ask me!!!takes a few minutes to do!! might need some sealer and flow coat though!!!

Cheers.


When I put my motor on I found the highest up, "last hole on the botom" was the best height before I even put it on the water, all sikaflexed and 2 pac painted, transom pad sealed all around too

so the problem is with the lousy set up that was done in 78. weather it was because the old jonno 85 Javlin leg height or they wanted it set up for sking, or they just didn't know what we know today I don't know.

If you look at a permatrim fr the rear they have a slight dome shape to it,
as it sits right now the Cav plate is running just on top of the water then the permtrim drops itself back into the water on the outside edges (about 50-70 mm) plus the turned down flaps, this is the only area I'm really tring to fix.

But as I've said it's very close to where I want it and for the sake of pulling the motor off plugging old holes and drilling new just isn't worth it.
Cheers

Roughasguts
23-11-2009, 10:19 AM
Fair enough then, I agree it would be a fair bit of bother for little or no benefit.

Cheers.

John Buoy
23-11-2009, 05:27 PM
I loved the permatrims so much so
that i got 2 of em :D ;D
Very neat idea on the spacings 8-)


http://img337.imageshack.us/img337/9729/permatrims003.jpg (http://img337.imageshack.us/i/permatrims003.jpg/)

Regards Frank