Aerotec transom replacement advice please

[Curlycraig]

Apologies in advance for the long post, but forgive me, the life of our beloved Aerotec is at stake!

This forum was incredibly helpful a few years back when the floor peeled away from our 1999 Aerotec 380, and following advice I successfully repaired it. The transom has now followed suit with the plywood soft in some areas. i.e. we need to replace the transom as well as a reglue.

The boat is too old to justify a professional repair and we don’t have the money currently to buy a used replacement. So it’s either a DIY repair or we say goodbye to boating for a couple of years, by which time a couple of our teen children will have left home :-(.

I realise the transom is more challenging than repairing the floor but I’m comfortable working with materials and am ready to spend the time to make sure I do it well - I’m not keen to see the engine falling off at speed! I’ve spent some time looking at threads which have already helped and I’m all ears for advice (particularly aerotec transom specific) but have some immediate ‘what would you do if you were me?’ questions:

- We don’t have a garage or shed, and I was lucky to have a spell of May hot dry weather when I reattached the floor. That is unlikely to be the case over the forthcoming Easter holidays. I can set up an event shelter with sidewalls that will be dry inside, but we’ll still have early spring temperatures and normal humidity . So, how critical is the recommended low humidity/warm temperature for the 2 part glue? (I used Polymarine for the floor). Any comments or ideas welcomed.

- The transom is 30mm plywood and every quality supplier I’ve searched for online seems to offer a maximum thickness of 25mm. Any suggestions as to where I might find 30mm of roughly the correct dimensions for the aerotec transom? I’ve read about glueing 15mm boards together, or using 30mm birch ply off amazon and then sealing with epoxy. Does anyone have any experience with these approaches, or suppliers I may have missed, or places to source used 30mm ply?

- We run the Aerotec with a 15hp Yamaha 2-stroke and have tried various ways to reduce the transom splash, the most recent being raising the outboard mounting position by 30mm. Given I now have a clean sheet to work with, any other redesign suggestions?

All comments or suggestions welcomed and hugely appreciated...

[Max...]

Not a lot you can do regarding splashing in regards to the transom if you have raised the engine all you can as it's due to the unique rear V floor channelling water against the leg.

Other solutions short of adding spoilers to the rear floor are to fit a deflector to the bottom of the transom or to the engine leg. In the end after much experimenting the simplest for me was the piece below, but check this topic for other ideas:

https://www.rib.net/forum/f50/aerote...tml#post750340

[Fenlander]

To make a worthwhile job you need to "dismantle" every part of the transom attachments from the tubes/transom and from each other... clean it all up and glue with great care.

I think temp and humidity is crucial so I'd not take a chance on that... needs to be right or all the hard work could be wasted.

Re transom wood I'd try and keep to good quality and personally not be against laminating two sheets (say 12mm+18mm) with waterproof glue if that was the only way to get the thickness.

Re splashing I've been using a Yamaha 15hp 2-stroke and the splash is almost zero with the 50mm lift I have as in the image below. There is no ventilation issue at any time.

This 50mm lift is 15mm below the level you'd get with a straight across transom so unless you are after a totally original job I'd think of constructing the transom straight across at the top then notching it in the clamp area by say 10mm to start then reduce after trial runs to the point there is no (or acceptable) ventilation in turns or a chop.

See posts #69-#78 in this thread to see more detail.

https://www.rib.net/forum/f50/aerote...e-71528-2.html

[bomberman]

Hi Curlycraig, to answer the What if I was in your position question, I was and decided to have a go, re glueing the transom and floor (I did document on here, not sure if you have seen it). As Fenlander has said, it isnt worth the risk of operating outside of the recommended conditions for the application of the adhesive....as I understand using it below the recommended temperature or above the humidity levels create problems with moisture. Using above the recommended temperature increases the speed at which it goes off....which may mean you don't have the time to mix and apply before it goes off (not that it will be a problem at Easter in the UK!!)
In some respects undertaking the task outside minimises problems with the vapours from glue and solvents although it may mean it is outside for a few days depending on your luck with the conditions falling in line for temp and humidity. I would definitely make sure you have some help for the glueing part as it is a challenge getting everything back to where it was before it was removed.

[bomberman]

https://www.rib.net/forum/f50/bombar...oor-77045.html

[Curlycraig]

Brilliant - thanks so much Max, Fenlander and Bomberman. Incredibly helpful; I'll respond to all in this post.

Max, Fenlander, it's great to have the reassurance on the transom raise, and the approach of going straight across and then dropping 10mm at a time makes a lot of sense. We have a steering assembly which I imagine pushes the centre of gravity forward, so testing and adjusting will allow us to find the right height for our particular setup.

Fenlander, it's super helpful to hear that you'd prioritise quality of ply over getting one piece of 30mm. I'll look into getting some quality marine ply and waterproof glue to laminate with. Any particular reason for suggesting 12mm & 18mm over 2 x 15mm?. I'm anticipating having to buy a larger sheet than the transom size I need so it may be cheaper to go with 2 x 15mm.
PS Replacing the transom will at least deal with the 'riser block envy' I experienced when comparing your elegant work compared with my job ;-).

I really like the splash plate thinking Max and while reading the thread started getting excited about fashioning one for the engine or transom from your guides. And then reminded myself that I need to fix the transom first! I think a combination of the transom raise and splash guard will help cope with the more varied weight loads between one to five people now the children are all over 80kg. In any case from your comments it looks like something that I can tackle once I've got the boat back on the water, which is great to know now.

Bomberman and Fenlander, your advice not to take chances with humidity and temperature does make sense even though it does present a problem. I'm now working through Bomberman's fantastic overview to see if I can sequence the project to keep the messy stripping and cleaning phase outside, and (assuming a marriage risking negotiation goes OK), bring the whole lot into the living room in for some carefully planned days of glueing, assembly and drying. Though taking over the Xbox and TV room until the job is finished does increase the chances of getting that extra pair of hands with the assembly :-)

Thanks again to all

[bomberman]

Hi Curlycraig, I would maybe reconsider any glueing or solvent work in the living room!!....it really is potent stuff and you or family don't want to be breathing in the vapours....I did mine in quite a ventilated garage and we had to mask up with the appropriate filters. Maybe move the xbox and TV outside to ensure the help!!!

[Fenlander]

No particular reason re my 18+12mm ply... it's just I tend to think of 18mm as the base thickness when doing a job and add to that as reqd... but yes you will get far more value out of a sheet if cutting from 15mm.

[beamishken]

Personally I wouldn't be too fixated on marine ply if funds are tight. Unless you buy really top notch like robbins elite which is eyewateringly expensive then what you get is little better than bog standard wbp from a builders merchants. If you can buy 15mm then I'd definitely go that route then you can buy a single sheet & have less waste than buying 2 odd sheets. If you use wbp & fill any small voids & seal realy well it will be fine for a fraction of the cost of quality marine ply and still last a long time. Definitely a good time to increase the transom height to improve the splash issue.

[Max...]

I'd also look at some of the specialist pre-laminated boarding products out there from more specialist suppliers - some come with man made face layers etc.