Bolting Outboard onto Transom

garethdeb

garethdeb

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Hi Folks
This might be a stupid question but then I'm generally full of them!
Do I NEED to bolt my outboard to the transom? It's a Mariner 40 so really heavy anyway and it's securely stored so highly unlikely to get lifted so do I need to drill holes on my transom to bolt through as well as the clamps?
Basically, I'm scared witless of drilling into the hull so if I can avoid doing it then I will.
Many thanks and regards all
Gareth
 
This really depends on where you keep your boat and engine, I had a 35hp engine stolen years ago, it was not bolted down. I have a 25hp on a fishing boat now, it is bolted through the transom with ss bolts and the nuts are welded to the bolts. If they want to nick it they have to chainsaw the transom off! IMHO any engine over 15hp should be bolted through the transom, it is no big deal, far more secure than relying on a couple of clamps to hold the engine on.
 
Davy_S said:
This really depends on where you keep your boat and engine, I had a 35hp engine stolen years ago, it was not bolted down. I have a 25hp on a fishing boat now, it is bolted through the transom with ss bolts and the nuts are welded to the bolts. If they want to nick it they have to chainsaw the transom off! IMHO any engine over 15hp should be bolted through the transom, it is no big deal, far more secure than relying on a couple of clamps to hold the engine on.
Click to expand...

I'd agree with the security side of it. However, standard practice for stealing outboards is the chainsaw through the transom method :(
 
I'd agree with the security side of it. However, standard practice for stealing outboards is the chainsaw through the transom method
Click to expand...

My boat is parked in front of a Taverna, I can assure you that you would be shot should you attempt to chainsaw my transom off!:D
 
Thanks guys. Security wise I have a huge great cable lock running through the engine handle and onto the trailer which would need an angle grinder to get through and it's parked right outside my bedroom window so I'm pretty happy with the security. My only concern is relying solely on the clamp to keep the engine in place especially if I wind her up out in the Solent. I REALLY don't want to drill through though as the old girl's obviously had a few different engines in her time so there's quite a few old filled in holes.
Still, I suppose a couple of stainless bolts aren't going to cost the earth huh, I'm just scared witless of letting my drill anywhere near the hull!!
Many thanks and regards
Gareth
 
JUST A REMINDER:

The most common cause of transom failure is holes drilled through the timber and not being sealed.

The best method of sealing transom penetrations is to drill 6 mm oversize and fill with epoxy resin mixed with micro fibres (not balloons) and re drill to the required size. This leaves a 3 mm seal between bolt and ply.

Methodology:
Push mix through the hole, when you have a solid mass on the other side, remove with a flat scraper and tape over the area to prevent any sagging, do the same on the outside, but remove any excess resin before it cures.

Good luck.
 
As PCUK says the owners manual states that the engine must be secured to the transom with 4 bolts through the holes provided in the clamp bracket

See page 7
 
Just to muddy the waters, I launched on Friday for the first time with brand new Tohatsu 15hp as auxiliary. To cut a long story short, we had to use it after 5 mins as we couldn't get the main engine to start. After about 2 mins of chugging along nicely, the engine took a leap into the air and into the briny. If it wasn't for the rope I had tied to the fender bracket and a 14 year old grabbing and holding on for dear life, we would have lost it (56kg weight). I went straight back to the engineer who fitted it and demanded it be bolted on (after it had been cleaned out) He used 2 bolts as he thought the bottom 2 would potentially crack the transom the way they were positioned but I don't think it will fall off now as I watched him break sweat tightening the clamps then the nuts on the bolts. My advice-get a professional to bolt it on. If we had used it in earnest in a storm we would have been stuffed!
 
Hi,
In years gone by they thought nothing of hanging a 40 horse just on the clamps, however it is much better to bolt it on, I have seen a couple of engines jump off over the years, (especially during sharp turns) I wouldn't be too concerned about putting a drill through the transom (it is after all generally the done thing) but als oldsaltoz says it is very important that they are sealed correctly, loads of older boats have rotten transoms due to old holes that have not been sealed properly, also most owners do not realise that they have rotten transoms because they still look great from the outside.
Any signs of stress cracking on either side of the engine well should be examined further just in case, as this is where a weak transom will usually start to show first.

Hope This is of some help
Phil.
 
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