Aerotec 380 maiden voyage - Page 2

Boatozzy · 29 May 2018, 15:36

Hi all,

I am very open to suggestions on here how to fix the issue, but if I can't fix it then its no problem. I could only get to the speeds we were going yesterday for the issue to happen on relatively calm seas. I spent most of the time on the plane at just over half throttle without the issue as water only kicked up towards full throttle which I don't intend to use all of the time.

What I will do is rig up next time with 2 up and take a couple of sizes of wood as Fenlander suggested. Happy to post videos/pic on a new thread (or existing one if someone can point me in the right direction) to show the issue and whether adjusting weight, trim or outboard height makes any difference

Stevie Bill · 29 May 2018, 17:41

A couple of YouTube vids showing the same problem on other boats: https://youtu.be/oNWo_qDpNqo and https://youtu.be/AyJzC335kQU hope these links work.
I guess a moulding issue might be involved, although I'm not sure that the moulding tolerance could make that much difference? I suspect that part of the problem may be that the transom is raked at an angle rather than being vertical. As a result the engine leg is some distance behind the boat when trimmed vertical if that makes sense. Water escaping the downward pressure of the hull will rise and cause a wave behind the boat. If the engine leg is catching the top of this wave... Could that cause the upwelling at the transom? Combined with a small splash plate which fails to disperse the rising water... And an engine leg which is currently mounted too low, so catching a lot of water... Various things to try, but I still don't think I should have to do this for an outfit that was bought new...

jeffstevens763@g · 29 May 2018, 17:46

last years scottish sib outing i picked up a small wrapper it lay in the eddie next to the transom i couldn't believe how much water it threw up back into my always dry stern doesn't take much of an imperfection.

Poly · 30 May 2018, 08:14

Stevie never had anything like that, with either it’s current or previous engine height (1” lower). I’ll grab some pics next time I’m at the boat. If it is the size of splash plate on the leg, can you not fashion something to increase (thinking along the lines of dolefins that people use for improved lift)?

Stevie Bill · 30 May 2018, 08:59

Poly:the doelfins fit to the anti ventilation plate... If I did that with the outboard as low as it is currently mounted, I fear it could lift the back of the boat completely out of the water! A previous discussion on here about the aerotec suffering similar issues had a few ideas. I think several tried to bodge a plate to fit around the splash guard... Jeffstevens may have been one?
The guy who supplied my outfit is trying to speak with someone else who apparently suffered similar issues with this boat/engine combo (!!!!! Why is he still supplying???!!!) and then make a saddle for me to fit and raise the outboard... If that doesn't work, then I'm already making a template to make a splash guard extender for the engine from an old hdpe filleting board I have in the garage... If that doesn't work, then I may need to think about fitting something across the rear of the transom on the boat... Or changing the engine... A 2 stroke yam 20 seems about right from what I've read on here☺.

Fenlander · 30 May 2018, 09:27

>>> I think several tried to bodge a plate to fit around the splash guard

It may have been the trials of various mods made by Max for his Aerotec that you are thinking of... although I reckon he'd like to be thought of as on the refined side of bodging!

Here is the thread from a couple of years ago with the most info on transom splash and mods...

http://www.rib.net/forum/f50/aerotec...sue-71528.html

Stevie Bill · 30 May 2018, 10:19

.... mods made by Max for his Aerotec that you are thinking of... although I reckon he'd like to be thought of as on the refined side of bodging!

Here is the thread from a couple of years ago with the most info....

Absolutely brilliant fenlander, thank you! I had obviously remembered reading all this some time but thought it much longer ago... Most recent threads just a year ago. And yes, it was the images of Max's splash plate that stuck in my mind. The various transom baffles look even better (and possible easier to fashion an attachment that won't just fall off!)
Just waiting on the transom block now before making my own mods. I have zero camera skill but will try to put some pics up in a few weeks for those interested.
This forum - and the very helpful people on it - are fantastic!

Max... · 02 June 2018, 22:58

Been off on the last week (fab time down on the Dart) and the transom anti-splash mod I last did two years ago is still intact and going strong - does not stop splashing but sends it out back and zero comes over the transom.

http://www.rib.net/forum/f50/rigging...tml#post715124

Boatozzy · 03 June 2018, 23:07

Thanks Max et al for the info. I will let you know how I get on

Boatozzy · 15 July 2018, 21:18

Hi all, went out today and I have found a solution to the splash issue. I simply set the trim to the highest setting which stopped the splash. This was tested with 2 up and 4 up with no issue.

We had another great day out today. We travelled our furthest distance yet from Mersea up to Frinton then back via Jaywick for some lunch 50+km round trip

We have always been on the sea when the tide was coming in but today we were out when the tide was going out (against the wind) as well. I feel confident on the sea now, however I felt a little nervous at times when we passed through some really choppy conditions off the coast. I have been out in stronger winds however the waves today were like none I have experienced before and quite challenging.

I lost my second VHF radio today as well (not sure how) and the Aerotec wheel suffered a puncture.

All in all a good day and more experience under the belt!

Fenlander · 15 July 2018, 21:37

Good to hear you had such a long outing. Where was it choppy in particular... near Mersea?

Boatozzy · 15 July 2018, 22:04

Cutting across from Lee-Over-Sands to East Mersea. The chop was worst around that corner of Lee-Over-Sands.

It was also quite choppy off West Mersea as you head into the Black Water river.

Fenlander · 15 July 2018, 22:21

The shallows run out quite a long way from the Lee-over-Sands headland... perhaps 0.5Nm... also from the south of Mersea perhaps up to 1Nm... and similarly from the East of the Bradwell on Sea peninsular well over 1Nm.

At various tide/wind states it can get much rougher over these patches than a little further out in deeper water.

In a way it's against human nature to go further out to sea when it's already rough but it can help to take a wider course.

Max... · 16 July 2018, 11:15

Always a good idea with a VHF handheld as well as clipping it to your LJ as normal to fix a Paracord loop to it and clip this on too. No chance of losing it then and could be critical if you end up MOB.

Poly · 23 July 2018, 23:26

Quote:

Originally Posted by Stevie Bill

Oh... And I should point out... This not just occasional splashing. At speed, this is a steady, high volume inrush of water over the transom between the engine clamps. Several litres per second. Because it happens at speed when the boat is running high and almost flat, I don't think weight distribution in the hard boat makes as much if any difference as it seems to have done with fenlanders Sib. Certainly I have not been able to solve it by shifting my own not inconsiderable weight forward...

Stevie - now my son is showing vague competence at helming I finally plucked up the courage to spend some time looking over the transom rather than worrying what he might hit.

With the boat relatively lightly loaded (I have a heavy console with my own heavy jockey seat contraption including battery, carry two anchors, c.50L of fuel upfront) a very skinny 14 yr old, and a rather less skinny old bloke, but well trimmed there is very little splashing against the engine leg (long shaft set about 20mm above the top of transom). I think that was running at 3rd pin out.

However, when we add a 10yr old, and a smaller adult, a heap more stuff - including a 25+kg canoe, and probably another 25kg of stuff up front, and probably 10 L of water it had shipped over the back she was struggling to get on the plane especially when he was too light on the throttle. There was a lot of splashing then, although none actually made it in the boat I could see how slightly differently configured it could.

We also tested it 2 up with the engine in shallow drive mode - again it struggled to get on the plane properly and was splashing like mad (albeit not coming on board). Not sure if that helps at all.

Stevie Bill · 24 July 2018, 11:15

Thanks for this Poly... There must be something radically different between the engines fitted. I have now fitted a booster seat to raise my 20HP O/B about 4cm. I can run without the transom overflow in most conditions, but the angry turmoil behind the boat when travelling rapidly remains quite troubling. I am certain something (the engine leg) is creating excessive drag and the foaming roiling water is often just inches from the overflow scenario.... Even with the booster, the anti ventilation plate is still sitting about 5cm or thereabouts below the line of the keel. Either a replacement transom (with 8cm higher threshold) or a new engine (with shorter leg) seem to be the only options remaining. I will be fitting some splash diverter plates (made from a section of plastic guttering) to the transom sometime in the next month or so and this may reduce the height of troubled waters, but it isn't going to fix the problem. But I can live with it for now. By the way... I carry a minimum of 120kg ballast when I'm in the boat - at least until my diet starts to take effect!

jeffstevens763@g · 24 July 2018, 12:34

i noticed this thought i would stick in here the 390 seems to dig in at the stern quite a lot would a dolefin help in this scenario to lift the stern just a thought.
in contrast the 450 seems a lot more level.

https://www.youtube.com/watch?v=-tZCFnz7Px8