Aerotec transom splash issue. - Page 5

Fenlander · 13 October 2018, 21:00

Well our last trip of the season just completed and the transom mod a complete success. It was warm but force 5/6... very gusty and rough. Despite the conditions up and down waves and in turns no ventilation at all... and most of all no splash over the OB or transom... just the usual untidy wake centre.

It's weird why they designed the transom centre so low... with a bit of on water testing Bombard could have realised across a wide range of OB makes/sizes it could have been left almost straight.

I also lifted the Garmin transducer about the same amount and that's cuts its splash loads too while keeping the depth reading OK. Don't know if I was imagining it but the whole effect of these mods seemed to make the outfit feel a little more lively.

smallribber · 29 October 2018, 08:00

As others have said Fenlander. Very neat work and I am glad it worked out well on the test

Aero_Hansel_420 · 30 April 2019, 10:03

Hey Guys,

not yet a splash issue. I am new member here and just bought a 420 Aerotec from 2000 in fairly good condition, better late then never

.

My plan is to use the boat as a little explorer and adventure vehicle here in the Baltic. Here is my issue, I try to keep weight to a minimum this is why I will convert the long shaft transom to short. What are your suggestions to go about it? Should I just bring the cav plate in line with the tip of the V bottom cut out what ever is needed and hope for the best?

Engine is an 2T Yamaha 20 63L.

Thanks to everyone contributing to the Aerotec knowledge here! I was lurking/reading a fair bit before coming across my new 420.

Big Al C · 19 May 2019, 22:20

Been looking at Chipko idea again from post 48,,,, and thought why not give it a go. I know my aerotec is pretty new, but I have no intentions of selling it any time soon.
So have been busy with some foam, black PVC and two part glue this weekend.

Big Al C · 19 May 2019, 22:31

http://www.rib.net/forum/attachment....1&d=1558301283

Will only be able to test out in a couple of weeks time,,,, have a day out on Windermere and report back with some pictures.

Gazzago · 20 May 2019, 08:51

Hi Al. Interesting idea. Very well executed. Be very interesting to see if it makes much difference.
Hopefully see you out on the water later this year [emoji1303].....splash free [emoji1]

Big Al C · 27 May 2019, 09:05

Quote:

Originally Posted by Gazzago

Hi Al. Interesting idea. Very well executed. Be very interesting to see if it makes much difference.
Hopefully see you out on the water later this year [emoji1303].....splash free [emoji1]

Went up to the lakes today. tried out the boat with 2 different outboard motors. tohstsu 25hp 2s and a mercury 15hp 2s, took 2 videos whilst hanging on to the phone and tiller. 15 shows the best results.
I can confirm that it works a treat, the water is coming straight out from transom and not shooting up at 45deg. Only problem I cannot upload the video to prove this at the moment. Will keep trying.

Big Al C · 27 May 2019, 10:27

Picture from video

jeffstevens763@g · 27 May 2019, 19:27

Hi Al

Out of interest if you had put the filler web inside the boat would the floor have pushed the hull skin out more level as I see it it seems to sag and not to tension in its original build position

Big Al C · 27 May 2019, 20:18

Hi Jeff,
The original build position is a radius with the HP deck pushing against it, some fit better than others,,,, no matter what you put between the HP deck and floor you'll still have a quarter radius from the bottom of the transom.
That's why I had to build it out on the outside.

jeffstevens763@g · 27 May 2019, 22:10

Quote:

Originally Posted by Big Al C

Hi Jeff,
The original build position is a radius with the HP deck pushing against it, some fit better than others,,,, no matter what you put between the HP deck and floor you'll still have a quarter radius from the bottom of the transom.
That's why I had to build it out on the outside.

I see so you would need massive force inside to achieve what you have building externally. Nice job by the way

Fenlander · 27 May 2019, 22:58

Big Al well done in being inventive enough to make that mod and prove what some of us have said for ages... Bombard could have addressed this issue years ago if they'd had the will.

Big Al C · 28 May 2019, 08:48

Quote:

Originally Posted by Fenlander

Big Al well done in being inventive enough to make that mod and prove what some of us have said for ages... Bombard could have addressed this issue years ago if they'd had the will.

At the end of the day it wasn't my idea.... Chipko had the vision in the first place. I just had the baxxx to glue stuff to the boat. Still cannot put the video on..... phone has done it in mp4 and its not usable on here and I don't have the know how to change it.

jeffstevens763@g · 28 May 2019, 11:03

Quote:

Originally Posted by Big Al C

At the end of the day it wasn't my idea.... Chipko had the vision in the first place. I just had the baxxx to glue stuff to the boat. Still cannot put the video on..... phone has done it in mp4 and its not usable on here and I don't have the know how to change it.

can you download onto youtube Al do it that way

Big Al C · 28 May 2019, 17:35

Quote:

Originally Posted by jeffstevens763@g

can you download onto youtube Al do it that way

Only ever watched stuff on there.... not looked at putting anything on. wouldn't know what to do.

Gazzago · 28 May 2019, 21:14

So pleased it worked. Was a risk glueing it up. But it’s paid off. A splash free Aerotec [emoji15] unheard of [emoji38]

Ps how were the launching wheels? [emoji6]

Locozodiac · 29 May 2019, 01:27

The post is way too long to fully read it. Would like to know if the back splash is out transom, side of transom or over transom ? Back splashes are usually due to badly inflated deep V keel and or motor sitting too deep, or a combo of both issues. Will need to determine which is causing the back splash ?

Happy Boating

Fenlander · 29 May 2019, 10:17

>>>way too long to fully read it.

If you look at my initial post #1, Chipko's post #48 and then Big Al's posts from #84 onwards you'll get the idea.

It seems the problem is caused by the unique way an Aerotec transom is shaped and how the fabric floor finishes to the transom. This produces water flow that rises up centrally in front of the outboard leg. How much this is a problem depends on each individual outboard leg and deflector plate design... it can be anything from an untidy wake to a near constant waterfall back into the boat when on the plane.

Lifting the outboard seems to help in most cases as does getting the trim right. Also the amount of splash depends how much load the Aerotec is carrying and how the boat itself is trimmed.

But as Big Al seems to have proved the hull shape at the transom is the major issue.

jeffstevens763@g · 29 May 2019, 10:50

personally if you need to know & people have spent time contributing i think you should read all posts it saves keep asking the same questions. this has been a problem to most aerotec owners and hats off to Big Al for pushing the design to overcome something that bombard must know about and should have addressed.

Stevie Bill · 29 May 2019, 11:28

Just to note the aerotec is not alone in suffering this issue. My funyak poly boat had awful transom overflow at speed until I fitted a 35mm riser and even with that there is still a substantial rooster tail... A splash guard will be fitted when I have the time. But squaring off the curvature of the hull/transom join to allow clean flow departure looks to be a much more promising line. Difficulty is fastening anything to the polyethylene Hull! I need to cogitate on it some more....