Bolting 9.8 hp to transom

[nnaabb22]

I have a 9.8 hp Nissan outboard on my 14 ft aluminum boat. I would like to bolt it to the transom (instead of just using the clamps) or added security while using it. There aren't any noticeable bolt holes. Any recommendations for how to bolt it to the transom? Is it possible?

 

[Neeves]

Welcome to the forum.

Why do you think bolts are going to make your O/B more secure. The nefarious will arrive with a couple of shifters - bolts are not a major deterrent. Why not invest in one of those security chains used to deter removal of motorbikes or buy a short length of decent high tensile chain (I can assure you it is very difficult to cut with bolt croppers (but the nefarious will have a battery driven angle grinder), or use stainless rigging wire (also susceptible to an angle grinder)..

You could remove the conventional clamps and use the same holes for the bolts (you could use security bolts (as they use in children's playground equipment). But then you will need a special spanner.

I'm obviously just being contrary - but the nefarious are resourceful - you need to think 'outside the box' - and maybe others will have much more useful comments.

Jonathan

 

[Stemar]

but the nefarious will have a battery driven angle grinder

In which case, perhaps better to lose the engine and leave the boat intact than lose the engine and a substantial lump of transom. I've heard of several cases where this has happened.

I'd be inclined to use a decent bike lock; your security doesn't have to be perfect, just better than the boat on the next mooring or good enough to persuade your insurer to cough up if the worst happens

 

[ghostlymoron]

At first we used to remove our 4hp Mariner and put it in the cabin under a bit of carpet when we left our Leisure 17 but that soon became a chore so used a square section chain and motor bike lock. Never stolen even though on easily accessible drying mooring.

 

[nnaabb22]

I should have clarified - I am not worried about it being stolen. The boat will either be in use or in my garage. I am concerned it will wiggle off while in use on the lake. Will it? My trolling motor has nearly done so - maybe it was not tightened down enough (I saw dents forming in the transom, so I figured it was tightened enough). Any other ways to make sure the outboard does not come free while in use?

 

[Stemar]

I should have clarified - I am not worried about it being stolen. The boat will either be in use or in my garage. I am concerned it will wiggle off while in use on the lake. Will it? My trolling motor has nearly done so - maybe it was not tightened down enough (I saw dents forming in the transom, so I figured it was tightened enough). Any other ways to make sure the outboard does not come free while in use?

It shouldn't - I'd expect the weight of the engine to be enough to keep it from escaping. It would wobble as you steer, but I wouldn't expect it to try and jump off, so tightening the screws down comfortably hand tight ought to be plenty. If it's working loose, my first thought would be to tie the handles of the screws together so they can't work undone. If that doesn't work, it would suggest that the threads are badly worn, In that case, helicoils in the OB bracket and new screws would be my fix of choice.

 

[Tranona]

If the aluminium is distorting then it needs reinforcing with a pad. Properly cramped no reason why a 9.8 should require bolting - which is why there is no provision on the clamp. Larger engines do indeed have holes for bolts because the extra power and torque may overcome the clamps.

 

[AngusMcDoon]

If the aluminium is distorting then it needs reinforcing with a pad. Properly cramped no reason why a 9.8 should require bolting - which is why there is no provision on the clamp. Larger engines do indeed have holes for bolts because the extra power and torque may overcome the clamps.

There are bolt holes on my Tohatsu 9.8, & they are used. My engine is clamped & bolted. The Yamaha 9.9 it replaced had bolt holes as well, so some 10hp models have them.

 

[John the kiwi]

It shouldn't - I'd expect the weight of the engine to be enough to keep it from escaping. It would wobble as you steer, but I wouldn't expect it to try and jump off, so tightening the screws down comfortably hand tight ought to be plenty. If it's working loose, my first thought would be to tie the handles of the screws together so they can't work undone. If that doesn't work, it would suggest that the threads are badly worn, In that case, helicoils in the OB bracket and new screws would be my fix of choice.

Um - plenty of youtube clips to prove you wrong. Here's one:

My outboard is bolted...

 

[William_H]

I trust the OP uses a lanyard on the motor anyway. Thus in the unlikely event the motor falls off. (or is dropped when removing or fitting) the motor will only fall the length of the lanyard. A motor can fairly easily be fixed if it goes in the water but obviously not if it goes for the deep six. Perhaps OP is worrying too much. (IMHO) ol'will

 

[AngusMcDoon]

I trust the OP uses a lanyard on the motor anyway. Thus in the unlikely event the motor falls off. (or is dropped when removing or fitting) the motor will only fall the length of the lanyard. A motor can fairly easily be fixed if it goes in the water but obviously not if it goes for the deep six. Perhaps OP is worrying too much. (IMHO) ol'will

It's probably not an economic fix if it swims while running at speed, especially if you pay someone else to do it. Replacing bent con rods & possibly holed pistons is major surgery.

 

[Iliade]

Perhaps you could squeeze a couple of U bolts through two unused pitch pin holes or even over the pitch pin? If not perhaps a couple of L bolts into said holes?

 

[ProDave]

Um - plenty of youtube clips to prove you wrong. Here's one:

My outboard is bolted...

The motorbike lock idea would at least have left it hanging so it could have been recovered and repaired.

 

[Praxinoscope]

deleated (wrong thread)

 

[Graham376]

There are bolt holes on my Tohatsu 9.8, & they are used. My engine is clamped & bolted.

My T9.8 also has bolt holes but not used. Tender in daily use for weeks on end and clamps have never slackened off in maybe 10 years with this and previous engine.

 

[Dellquay13]

padlock the two clamp handles together, so they can't unscrew?

 

[graham]

I have seen more than one outboard come off.

The instructions for my Honda 8 hp recommended bolting it on .

I would sandwich the aluminium between two plywood pads and bolt through the whole lot.

 

[nnaabb22]

Thanks for all the advice - when I take it out on the water I makes sure it is clamped tightly and zip tie the two screws together. I have seen the videos of the outboards jumping off, and wanted to be extra cautious (maybe overly cautious) since I'm out on the lake with young kids and don't want to row the boat back to shore. I'm not sure if the pictures provide enough detail to see if bolts would work. I appreciate the advice so far. Thank you.

 

[nnaabb22]

I have seen more than one outboard come off.

The instructions for my Honda 8 hp recommended bolting it on .

I would sandwich the aluminium between two plywood pads and bolt through the whole lot.

Graham - do you have a picture that shows what you mean? I am not quite following. Thank you.

 

[Refueler]

If the ally is being deformed by the clamps .... then its definitely tight !!

I would secure a hardwood pad so the clamps press on that. Usual Plywood is not hard enough and will 'squash' where clamps press. Another possibility is if someone's condemning an old Zodiac / Avon ... they usually have a hard plastic outboard pad screwed to the transom ... they make excellent pads for other boats use.

My Mariner 20 - when I bought it - had a security head on one clamp. The hand lever had been removed .. clamp replaced by the locking security version. It needed a key inserted into it to operate ... without it - the large barrel head just freewheeled.
The seller - who was the owner as I was given the Registration Doc for the engine ...... yes over here we can register the engine same as a car / boat etc. proving ownership .... he'd lost the key.

It took a whole grinder disc to cut that item out as the end with the cup washer was solid and not as the old clamp. It needed to cut the threaded part or work on the head itself.

As I see it ... apart from the security bolt holes most outboards have one ... replacing clamps with bolts is not so easy - as the outboard mount frame will not allow access to through bolt ... the outside verticals usually align with the clamps. even if you could, I don't see any advantage over using the single security bolt hole provided.