Aerotec 380 transom height mod.

[squiddy]

Couple pics to show off new permanent transom riser on my aerotec 380.

Extends transom by 3cm - fancy marine wood with fancy sikoflex and fancy marine screws.

First pic (from previous owner) is wildtype aerotec on her trailer, showing original transom shape. Pic of the riser being fitted and, finally, a pic of the job done and painted - all ready for the west coast in April!

She has a new shiny, slightly higher arse!! Hmm, now I wonder if I could manufacture the same for 'er indoors????


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[PeterM]

Very nice job - will be doing the same to mine in the next few weeks. I'll just have to out up with lots of spray tomorrow ..been and filled the petrol tank and got more this afternoon - roll on 5 pm !!

[squiddy]

Originally Posted by PeterM

Very nice job - will be doing the same to mine in the next few weeks. I'll just have to out up with lots of spray tomorrow ..been and filled the petrol tank and got more this afternoon - roll on 5 pm !!

Thank you. Sounds good , just chuck a block of wood in - until you do the permanent modding. Have fun!!!!!!

Do you happen to know how much you are raising your transom for your merc 25hp??

Just interested to know what heights required for other engines.

squiddy

[PeterM]

Between 2-3 cm seems to give the best results to reduce the waterfall over the transom so I start at 2 and spend an ahour or two with a few differant sized blocks before commiting. So far when I've run it fast I just pull the bungs so the water comes in and goes straight out again.

I probably wont be as well finished as yours - just raise the transom pads inside and out and block the middle gap with a bonded & screwed in bit of ply - suitably painted black.

[matt h]

looks great.. Heading to salcombe tomorrow so lookin forward to trying out the new bathtub!!

[davenport5]

I tried various size blocks on my 380 and it improved the spray but did not fully resolve it, but the prop is more prone to cavitation the higher it is. Courtesy of Mrs Bongy, I then tried to put a piece of pipe lagging in between the clamp brackets at the top of the transom and it totally resolved it by blocking the water path. I then lowered the outboard back to its standard condition with the lagging in place and still no spray. The lagging stays attached to the engine when removed so it's no hassle.

[PeterM]

Originally Posted by matt h

looks great.. Heading to salcombe tomorrow so lookin forward to trying out the new bathtub!!

test went well I think !

[squiddy]

Originally Posted by PeterM

test went well I think !

Nice one! Did you get it down to 0.5% splashback?

Davenport5, I stuck some cunning spray deflectors on the engine - these along with the raised transom do the job nicely. Wouldn't want to raise the engine another cm though.

[uny1965]

hi, any pics of these spray deflectors please, i've been suffering the same problem with my aerotec 380 and 18hp tohatsu. raised the motor 30mm and its more or less solved the problem, but still getting that little bit of water between the transom clamps. cheers

[PeterM]

Originally Posted by uny1965

hi, any pics of these spray deflectors please, i've been suffering the same problem with my aerotec 380 and 18hp tohatsu. raised the motor 30mm and its more or less solved the problem, but still getting that little bit of water between the transom clamps. cheers

If the engine raise works then I think with some pipe lagging problem solved ??

[Gaz]

Originally Posted by PeterM

Very nice job - will be doing the same to mine in the next few weeks. I'll just have to out up with lots of spray tomorrow ..been and filled the petrol tank and got more this afternoon - roll on 5 pm !!

Pete,

I'm filling my Bombard up with water at the moment when I'm driving at max speed.

When you have finished yours I would love to see it in person (I live in Poole).

Do you think that could be arranged?

Regards,

Gaz

[Gaz]

Originally Posted by davenport5

I tried various size blocks on my 380 and it improved the spray but did not fully resolve it, but the prop is more prone to cavitation the higher it is. Courtesy of Mrs Bongy, I then tried to put a piece of pipe lagging in between the clamp brackets at the top of the transom and it totally resolved it by blocking the water path. I then lowered the outboard back to its standard condition with the lagging in place and still no spray. The lagging stays attached to the engine when removed so it's no hassle.

Any chance of a photo?

I don't even know what 'pipe lagging' is, let alone how to fit it onto my transom :-)

I'm virtually incapable of DIY.

Are we talking a bit of spray here, or something more dramatic?

I've just upgraded the engine on my Aerotec 380 to a Mercury 25hp 2 stroke, with remote controls and cross bar steering. When I go to max speed the water absolutely gushes over the transom - bucket loads of it! It almost fills the boat and I have to slow down for a while to let the water flush out.

Would love to see other peoples photos and solutions to this problem.

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[Locozodiac]

Tohatsu, Mercury, ara natural water splashers, a tail design issue compared to Yam, need to raise transom untill water flow passes slightly under small upper plate once at full plane. The splash is produced when water flow hits the non cut tail portion, flow must pass through edge triangle, in mist cases will need to raise transom accordingly untill this is achieved.

With sib well inflated and ballanced driver must perform a visual check at back transom. Once height is correctly set no need to add water side splashers. This transon height fine tuning must be done under trial and error.

http://www.youtube.com/watch?v=oBeZj...ature=youtu.be

Happy Sibbing

[Gaz]

Originally Posted by Locozodiac

Tohatsu, Mercury, ara natural water splashers, a tail design issue compared to Yam, need to raise transom untill water flow passes slightly under small upper plate once at full plane. The splash is produced when water flow hits the non cut tail portion, flow must pass through edge triangle, in mist cases will need to raise transom accordingly untill this is achieved.

With sib well inflated and ballanced driver must perform a visual check at back transom. Once height is correctly set no need to add water side splashers. This transon height fine tuning must be done under trial and error.

Happy Sibbing

Many thanks, very helpful.

Just got to find someone who can raise it for me now, as my DIY skills are worse than non-existent!

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[PeterM]

Originally Posted by Gaz

Pete,

I'm filling my Bombard up with water at the moment when I'm driving at max speed.

When you have finished yours I would love to see it in person (I live in Poole).

Do you think that could be arranged?

Regards,

Gaz

Gaz ,I plan to be at home all weekend working on my sea rider. PM me and your welcome to come have a look.

Pete

[Locozodiac]

Originally Posted by uny1965

I've been suffering the same problem with my aerotec 380 and 18hp tohatsu. raised the motor 30mm and its more or less solved the problem, but still getting that little bit of water between the transom clamps. cheers

The splash is due to lower middle section design. You need to shim a bit higher transom untill water flow at wot passes slightly under small upper plate, engine must be trimed to be perpendicular at wot with sib well weight distributed and runing paralell to water surface, once there, water splashes will be solved for ever and ever, amen.

Happy Sibbing

[davenport5]

Originally Posted by Gaz

Any chance of a photo?

I don't even know what 'pipe lagging' is, let alone how to fit it onto my transom :-)

I'm virtually incapable of DIY.

Are we talking a bit of spray here, or something more dramatic?

I've just upgraded the engine on my Aerotec 380 to a Mercury 25hp 2 stroke, with remote controls and cross bar steering. When I go to max speed the water absolutely gushes over the transom - bucket loads of it! It almost fills the boat and I have to slow down for a while to let the water flush out.

Would love to see other peoples photos and solutions to this problem.

.

Gaz,

I have the same steering set-up as you and I found that adding a block to lift the outboard up helped but did not resolve the water gushing in. However, because we are sitting further forward than those using a tiller it caused a lot of cavitation so I removed it.

Mine is now totally dry by adding some foam. Sorry I don't have a photo. Pipe lagging is foam that you put around a pipe and you can buy it from a DIY store. Some of the Aerotec owners I go on Holiday have also now done it and it definitely improves it, but they use a tiller so still prefer the block as well.

I will try to describe what I have done. You need a piece of foam that is about 20mm thick, 40mm wide and about 250mm long. Tilt the engine up and place the foam to sit on top of the transom. You may need to cut to length. Then lower the engine on top of the foam and you get a good seal to the transom stopping the water. If you keep the foam a bit long then you can poke it in the form of the transom clamp castings. It will then stay there all the time, even when the outboard is removed.

Do you also have the bungs removed?

[Gaz]

Originally Posted by davenport5

Gaz,

I have the same steering set-up as you and I found that adding a block to lift the outboard up helped but did not resolve the water gushing in. However, because we are sitting further forward than those using a tiller it caused a lot of cavitation so I removed it.

Mine is now totally dry by adding some foam. Sorry I don't have a photo. Pipe lagging is foam that you put around a pipe and you can buy it from a DIY store. Some of the Aerotec owners I go on Holiday have also now done it and it definitely improves it, but they use a tiller so still prefer the block as well.

I will try to describe what I have done. You need a piece of foam that is about 20mm thick, 40mm wide and about 250mm long. Tilt the engine up and place the foam to sit on top of the transom. You may need to cut to length. Then lower the engine on top of the foam and you get a good seal to the transom stopping the water. If you keep the foam a bit long then you can poke it in the form of the transom clamp castings. It will then stay there all the time, even when the outboard is removed.

Do you also have the bungs removed?

Mmmm, I see what you are saying about the difference in the seating position, with the forward steering, and how that would affect engine height.

Yes, I have to remove the bungs or the water would just fill the boat up.

Thanks for warning me, and for giving me the tip.

I'm trying to visualize what you are saying. Is it the foam that is already shaped circular to fit around a pipe? And then you hook it over the transom (as you would the pipe), and it somehow creates a seal between the engine and transom? Is that the right idea?

Maybe if I give it a go, and then take a photo, you might be able to tell me if I've got the wrong end of the stick.

Thanks Davenport

(Where do you live? Or when are you next in the water? Maybe there could be some way that I could get eyes on your set up?)

.

[davenport5]

Originally Posted by Gaz

Mmmm, I see what you are saying about the difference in the seating position, with the forward steering, and how that would affect engine height.

Yes, I have to remove the bungs or the water would just fill the boat up.

Thanks for warning me, and for giving me the tip.

I'm trying to visualize what you are saying. Is it the foam that is already shaped circular to fit around a pipe? And then you hook it over the transom (as you would the pipe), and it somehow creates a seal between the engine and transom? Is that the right idea?

Maybe if I give it a go, and then take a photo, you might be able to tell me if I've got the wrong end of the stick.

Thanks Davenport

(Where do you live? Or when are you next in the water? Maybe there could be some way that I could get eyes on your set up?)

.

You are visualising it correctly, but I have cut and changed the shape of the foam so that it stays on the engine. I started with it hooked over the transom as you have put. It effectively creates a seal between the transom and the outboard and closes up the gap, which is where the water floods in from. When you lower the outboard from the tilted position onto the foam make sure it goes to its normal position and is not being held up by the foam.

I have also found that it is better to have the fuel tank at the back of the boat with it strapped to the transom to keep some weight at the back.

I am in the midlands and sadly not planning to use the boat again this year.

[Locozodiac]

Placing a foam at back transom will solve the back splash problem, on the other hand if using as factory delivered, tail will have more water drag and engine slight less rpm at wot, both issues lessening overall sib performance. If you want boating perfection, a transom rise as explained is the way to go specially if using portable Tohatsu, Mercury, Nissan engines which are same natural water splashers brothers if not corrected height seated.

This 360 sib with a Tohatsu 18 HP short shaft had horrible water splashes at back transom. Raised transom accordingly at shop, once engine was correct trimed and sib well ballanced, owner couldn't believe the difference once on plane.

Happy Boating