Aerotec transom splash issue. - Page 4

Firstrib · 17 June 2017, 22:52

I have

Fenlander · 17 June 2017, 23:01

I keep meaning to do a Big Al style thing but over the past year haven't had boat unpacked, tools and testing time on the water coinciding. We are running with the basic 20mm or so shim that is far as ours will come up without the OB clamps being off the plate.

However it is slightly academic as despite a messy looking wake the Suzuki DF20A gets so little water in even over a 3hrs period it's not an urgent issue.

When we were out the other weekend we had an additional (small) adult so were even more planted in the water at the bow than usual and there was the least splash I've seen so far.

But I will try and remember the tools/materials on our Devon holiday to try.

Firstrib · 17 June 2017, 23:01

Splash protector. The rivets didn't work in the end so used nuts and bolts. Mixed success. I think it works well. But then again it didn't solve it completely. Perhaps o need to raise transom as welll

Fenlander · 17 June 2017, 23:20

Hope things are well with you and your sibbing Firstrib. Thanks for posting the shield mod pics.

I see what you mean... there is still a good amount of the upside down shower I remember from our Mariner 15 on the Aerotec. It would get into the engine through the drain holes so I'd always gently rinse under the cowl with fresh water on return home then use an anti-corrosion spray to keep the OB internals nice.

falcon0310 · 17 June 2017, 23:47

works fine with 20 mm perspex

Yabadabadoo · 18 June 2017, 00:02

I wonder as Falcon says if a stiffer product would help, you don't want it so brittle but there's bend in Firstribs mod with the water pressure pushing past. Could a bigger wider plate work, or a thinner rubber or PVC spray deck?

Max... · 18 June 2017, 16:50

I personally would not use something hard as you want it to give a little for packing etc - my first one (made with the Bosch trimmer guard) cracked so just re-made it to the exact same dimensions.

Original making part here:

http://www.rib.net/forum/f50/bombard...s-62326-7.html

I never throw anything away that might be useful and this time it was a piece cut from my old Disco front bumper!

This is for the 'L' and the splash guard rivetted on is the same piece of studded rubber flooring.

Rigid but flexible. New one below.

I have a 28mm block on the transom - tallest I could go without much modding as the engine clamps won't fit otherwise.

Would like to go higher but the major modding puts me off as does the fact it cavitates on really sharp turns with a 28mm block anyway.

Max... · 18 June 2017, 16:55

HDPE might be a good material for these guards too?

http://www.ebay.co.uk/itm/HDPE-SHEET...3D361061245368

The other guard made (again treating the symptoms rather than a cure) was detailed in this part:

http://www.rib.net/forum/f50/bombard...s-62326-8.html

Possibly worked better than the transom guard but it eventually fell off and I have not made another yet.

Fenlander · 03 September 2018, 22:43

Ah well here we go again.

My new 10hp Mariner is proving far more splashy than the Suzuki 20 which hardly suffered... and more but in a different way to the old Mariner 15 2-stroke.

With the Mariner 10hp it doesn't throw the water back in the boat but the spray flies up all over the motor added to that from the Garmin transducer which also needs a mod.

I have been using a standard 18mm shim I've had on years but will now replace that with a more substantial block raising it about 45mm. I will lift the inner and outer transom pads to the top of the new block and this will still mean the clamp screw washers/pads will be clamping … only just though... on the original transom not the block.

I've found a piece of oak (or perhaps walnut) that is close to size so will fettle that into position over the next few days.

Re image old shim will be removed and new block trimmed in height by about 5mm.

Fenlander · 04 September 2018, 23:39

Inner and outer pads off. Old screw holes filled with dowel and waterproof glue. New wood rough cut to shape.

Fenlander · 04 September 2018, 23:43

Trimming wood to correct shape and height. Clamped on to ensure fit and hold for accurately drilling screw holes in from top.

Fenlander · 04 September 2018, 23:47

Riser block screwed down and rear pad re-attached at a height to match. A very small bead of gap filling waterproof glue was run around the edges of the block lower face to seal any edge imperfections.

Just the inner alloy pad to re-fix tomorrow then paint.

Fenlander · 05 September 2018, 21:39

Today I filled the existing holes from bolting my previous Suzuki on... wooden dowels and waterproof glue. Aso drilled new holes to bolt on the current Mariner 9.9... its only a couple of extra minutes to puts the bolts in at set up time and I feel happier with the extra security given the 45mm lift.

Image of how the AV plate and transom bottom align with the 45mm lift in place.

hymerbeliever · 06 September 2018, 08:09

That looks really neat but 45mm seems a lot: did you try it first? I got the impression that the 30mm block I used on holiday might be too much but didn’t pay much attention to how the cav plate was sitting relative to the keel. My wake was also like a big rearward water cannon plume angled about 400mm up and that made me think how much energy was being wasted doing that rather than pushing the boat forwards. Great boat otherwise.

Fenlander · 06 September 2018, 11:20

>>>45mm seems a lot

It might but...

The original shim I've had on years was already 18mm and still loads of splash with this OB so my increase from current is only 27mm. Also in that last photo the 45mm rise brings the AV plate in line with the lower edge of the transom which is the correct starting point for setup testing. And if you look at others above they have gone to 50-65mm in their experiments with different OBs.

No I haven't tried it on the water as the 45mm lift was too great to try with a temp block as the OB clamps wouldn't have been gripping enough of the transom... so to be secure I had to do the whole mod. And re the height I had planned it so all I have to do is remove the three vertical screws then I can plane it to a lower dimension if needed and just put the screws back in. Had I made the lift smaller and it not been enough I'd need to do all the construction again with 10 inner/outer pad screw holes to plug.

Frustratingly it may be 3 weeks before we can get out to test it.

bomberman · 06 September 2018, 20:28

That's some tidy work fenlander. When I first used my aerotec I had what I can only describe as a waterfall coming over the back at full speed(couldn't go it for long before it was a mid sea paddling pool!!!). I seem to recall I changed the engine trim by one hole and now I don't get anything at all regardless how it is loaded. Engine is suzuki dt15 and there has been no mods/raised blocks on transom.

Fenlander · 06 September 2018, 20:55

Thanks... and it would be even tidier now had it not poured with rain as I was about to mask up for painting.

Your experience is typically atypical... it seems every different OB make/model/HP combined with different loads carried and SIB trim plus OB trim produces a different splash result.

Fenlander · 10 September 2018, 16:44

Eventually pulled it into the garage to re-paint the transom... and all complete now. Just need to find a free weekend asap to trial.

PeteG · 10 September 2018, 22:00

Looks a very professional job David. Fingers crossed it produces the desired effect

Yabadabadoo · 15 September 2018, 10:14

Thought I'd share this http://www.dillon-racing.com/jackplate/index-m.htm as it's along the lines of this thread, not ideal as a long term set up unless you're racing?

A simplified version could be knocked up by others next time to test running height of outboards.

I found it while searching for 'open fishing boats that will fit a short shaft outboard' as I might have a option to buy a cheap small open boat, but ideally don't want to run two outboards. - That alone might be another thread, more research to see if it's an idiot idea or not.