Aerotec transom splash issue.

[paintman]

Originally Posted by jeffstevens763@g

i used one years ago to get a sib on the plane with three divers on board with success but how much top end we lost i dont know but that wasn't the issue so a result for us,
the one we had was a wrap around not two separate fins if they are still available with a slight mod you dont have to drill the cav plate with just a strap across the back if that makes sense.
i dont like drilling the cav plate as it shows you have been needing more out of the engine and its possibly had an hard life plus corrosion issuess.

just a thought if anyone is into making one a piece of HDPE with a slot in it for the cav plate slid on will work, start fairly large and keep cutting it down till you get the right size the slot can be made with a soldering iron to quite a good finish and the sides that are cut smoothed with a wood smoothing plane.
cheers

Although it would need the plate drilling you could make up an ally plate similar to these instead of doel fins:
https://www.permatrims.com/

[Neil Harvey]

Originally Posted by SeanKent

It's interesting how the aerotec always needs a tramsom shim.

Neil how comes you wouldn't use your 25 on the aerotec ?

It's a long shaft :-(
I toyed with the idea of making a large enough extension plate to raise it about 6.5", but was advised against it. I am now wondering if using a long shaft might work, the prop would be that much lower maybe the splash issue would disappear. But, it's likely to impact balance of the boat, with the power being that much lower down... May still give it a go though, I got the 25 service finished today so it is pumping water again after years of no use, I attached the tiller again so I can now control it, and "just" need to wire in a kill cord to make it safe.

[SeanKent]

Hmm all this messing around with engine height does put me off a bit.

If I do manage to get an aerotec, I'll be looking to pick brains on here as to best way to deal with the splash.

[SeanKent]

Originally Posted by Neil Harvey

It's a long shaft :-(
I toyed with the idea of making a large enough extension plate to raise it about 6.5", but was advised against it. I am now wondering if using a long shaft might work, the prop would be that much lower maybe the splash issue would disappear. But, it's likely to impact balance of the boat, with the power being that much lower down... May still give it a go though, I got the 25 service finished today so it is pumping water again after years of no use, I attached the tiller again so I can now control it, and "just" need to wire in a kill cord to make it safe.

Can't you change the leg?

[Neil Harvey]

Originally Posted by SeanKent

Can't you change the leg?

Probably, but not sure it's worthwhile on an early 80's engine...

[Stevem]

Originally Posted by SeanKent

Hmm all this messing around with engine height does put me off a bit.

If I do manage to get an aerotec, I'll be looking to pick brains on here as to best way to deal with the splash.

Hi Sean

I've had a 15hp mercury and a 25hp tohatsu on mine and they both required different shim heights but both totally acceptable after I raised the outboard.
I know it may sound a pain but I wouldn't let it put you off owning one.

[jeffstevens763@g]

Originally Posted by paintman

Although it would need the plate drilling you could make up an ally plate similar to these instead of doel fins:
https://www.permatrims.com/

thats the sort of thing i was suggesting made from hdpe sheet made tight enough to be slid on from the front of the motor cost would be less then a tenner bit of shaping and a slot for the cav plate cut in with a soldering iron or hot rope knife no drilling just a tight fit

[paintman]

I have reservations whether something similar without fixings & just relying on a tight fit would stay on for long as there is a fair amount of lift - certainly comes onto & stays on plane at lower speed than without.
Below the plate I can see a risk of prop contact should it work loose.

[jeffstevens763@g]

Originally Posted by paintman

I have reservations whether something similar without fixings & just relying on a tight fit would stay on for long as there is a fair amount of lift - certainly comes onto & stays on plane at lower speed than without.
Below the plate I can see a risk of prop contact should it work loose.

how can it come off you make the grove deep enough so it cant twist so minimal gap between each side as near to the main leg as possible, its pushed on from the front the way of travel at speed pushing it on [horse shoe shape] nothing to stop putting a captivation across at the back for added security. it could be made in two parts and bolted together and if HDPE is used cheep enough to have a few try's. you could also sikaflex the gap and glue on loads of options.

cheers

[Yabadabadoo]

Two design options

[SeanKent]

Originally Posted by Yabadabadoo

Two design options

Love those designs

I have an umbrella press, maybe I could print them up as an Aerotec accessory .

[Yabadabadoo]

Sounds like (lately) the best Areotec accessory is glue! :-)

[Fenlander]

Do bear in mind all I know is... 1) my Suzuki 20 doesn't splash at a low transom raiser height which would have caused the Mercury 15 to splash loads... and 2) my Suzuki has a much larger anti-ventilation plate plus a larger upper water deflector plate.

I don't know which of the plates being larger is making the difference... if it's the upper plate that would be far easier to enlarge.

[chipko]

[QUOTE=SeanKent;710875]
SeanKent quoted
Hmm all this messing around with engine height does put me off a bit.



If I do manage to get an aerotec, I'll be looking to pick brains on here as to best way to deal with the splash.



Hi Sean,
It's not only Aerotec's that require tweaking engine height and trim.....all boats benefit, so don't let this put you off one.
As mentioned previously, we seem to get best results with AV plate about 10mm below keel. High enough to reduce drag from lower leg but low enough to limit ventilation to occasionally out of tight turns. Good for us in swell and chop, two up and often towing kneeboard or wakeboard.
Really is worth all the faffing, and you only have to do it once. Best and most exciting method is to hang over back of transom at WOT and look at water flow over lower leg / AV plate. A Go Pro on a stick also works, but much less exhilarating!
A few combo's here all with same 20 hp Suzuki motor.

Aerotec 365 (current stubby cone 380)
25mm spacer block on transom
Trim position 4 of 5.



Zodiac Zoom 350
20mm spacer block on transom
Trim position 3 of 5



F-Rib 375
10mm spacer block on transom.
Trim position 2 of 5

F-Rib really easy to set up as very clean/consistent water flow off hard hull.

[Fenlander]

Chipko great images to assist. When you say trim 4 of 5 with the Suzuki/Aerotec combo... is that 4 of 5 trimmed into the transon or out?

[chipko]

Fenlander, position 4 of 5, away from transom. Works OK on 3 also, so if there was a 3.5 that would be perfect.😀

[Fenlander]

I didn't mess during our first running in trip but something I'd forgotten to comment on in my report on the engine was that the Suzuki felt far heavier on the tiller than my old Mercury so I wondered if a trim change might help?

It was set in mid position.

[chipko]

That's interesting. Not noticed this on different trim settings, but must admit I prefer some steering friction so have dialled this in on the adjustment nut/lever.

[Fenlander]

Just diffeing preferences between us I guess. I don't usually have any steering damper on and like a free under the fingers feel for an outboard. Despite being free at rest with the damper off my Suzuki feels a little weighty under way.

[Neil Harvey]

Maybe due to the 33% additional power and the added weight?