Prop nut question

[Elessar]

my prop nuts have been working as anodes.

I will fix the electrical connection to the shafts, then I need some new nuts.

I need them by friday. A couple of questions.

It is a 2" shaft on a sealine. Is that enough to know the nut size? If not, what do I need to measure? I have the nut but can't get to the shaft.

Where can I buy them? Steel developments who are refurbing the props are not the answer.

TIA

 

[sunquest]

We bought our replacement props from Clements together with two new dome shaped prop nuts. I assume they judged the nut size from the taper in the props and yes our shafts are 2" not to be confused with 50mm. May be worth giving them a call

 

[jfm]

Mark, Boats.co.uk have loads on the shelf in Essex so a quick email to Nick Barke and a credit card number might result in 2 in a jiffy bag tomorrow. Lock washers too. What you need to measure is the diameter to the bottom of the thread groves, and the tpi which you can do with a ruler on a nut that big. If you're at the boat you have Hamble Propellers in Swanwick so you can drive round with the old nuts (never used them; just heard of them)

 

[Bandit]

Clements Marine, normally ex stock also get new tab washers.

Are the keys in perfect condition or have they hammered or have they gone pink as well?

To get a good fit when you replace the props use a grinding paste and engineers blue to fit properly.

Now you need to sort out protection for your shafts and props.

 

[Elessar]

Thanks all. Keys are OK. Can't grind the props as i will be diving to refit them. Will just have to grease and hope. (Thus the nuts being available not the shafts )

 

[burgundyben]

If still stuck, worth a mercy call to Hamble Propellors in Swanwick.

 

[djefabs]

Mark, Hamble Propellers are very worth a call/visit. they will probably have a pair on the shelf. Worst case they have the equipment to make them from your old patterns.

 

[splosh]

Mark,
If you don't get anywhere quickly then you need to call Teignbridge Propulsion in Teignmouth.
The are the original equipment supplier for your vessel.

 

[Bandit]

Grease is not the normal fit

 

[rosssavage]

Wot bandit said - do not grease the shafts!! It's a taper fit, so needs to be clean and dry. Grinding paste and engineers blue is the real proper way to get it right, but is probably overkill unless you know what you're doing and have the time to get it just right.

I got some 1" UNC prop nuts (1 1/2" shaft) from Norris marine about a month ago (just up the road from steel developments) but they probably won't have the dome type nuts as fitted to your Sealine. Worth a call if you're stuck though..

 

[Elessar]

Wot bandit said - do not grease the shafts!! It's a taper fit, so needs to be clean and dry. Grinding paste and engineers blue is the real proper way to get it right, but is probably overkill unless you know what you're doing and have the time to get it just right.

I got some 1" UNC prop nuts (1 1/2" shaft) from Norris marine about a month ago (just up the road from steel developments) but they probably won't have the dome type nuts as fitted to your Sealine. Worth a call if you're stuck though..

It's castled nuts on mine.
Ok why not grease? Even steel developments said "grind then grease" when I said I couldn't grind they said "just grease then". I'm not talking thick axle grease but a light smear. Surely it will help get it off next time?

 

[rosssavage]

It's a taper fit, that's why! The taper relies entirely on friction to transfer the energy from shaft to prop.

It won't help the prop come off next time - after a year or whatever under water spinning at 1500 rpm there will be none left. If the prop is hard to get off it means the taper is doing it's job. If it's really difficult to get off it's been overtightened and forced too far up the taper.

When I install a prop the shaft is religiously cleaned. Check it's dry and degreased, fit the prop and tighten the nut. I then leave it overnight to get the two components at the same temperature and go through a temperature cycle (warm day, cool night..in theory in the uk anyway!!) and let the taper settle. Next day I back the nut off and then retighten to the correct torque.

Depending on the relative temperatures of the two components on fitting, the taper may have got tighter (hence backing off nut) or looser (hence retighten to correct torque) over the temperature change period.

A good taper fit doesn't even need a nut or key to work, but they are used as good practice and a fail safe.

A taper is a precision interference fit, not just a bung it on and do it up as tight as you can job...

 

[rosssavage]

Norris may well have a nut if it's a standard castellated type - also Apex Fasteners in slough may have one.

Good luck getting it done in time!

 

[Bandit]

As Rossavage says.

No Grease a clean shaft, grind prop to shaft , most boat manufacturers don't bother unfortunately and check with engineers blue.

The fit is interference, the keyway is a last resort the very last thing you want is a prop loose on the shaft , hammering on the key and loosening the nut.

 

[Elessar]

Norris may well have a nut if it's a standard castellated type - also Apex Fasteners in slough may have one.

Good luck getting it done in time!

I called into Norris's on the way into London this morning. What a great place! Loads of stock of real boaty things, in an engineering workshop and no bling for sale. A proper boat shop.

"Its a dufunct thread. If we haven't got one, can you pop back later and we'll make one."

They had the 2 I wanted, and were apologetic about the price for these 2 perfect nuts that they had obviously made, and kept in stock. £70 inc vat for the pair did not seem at all unreasonable to me considering the size and work involved, leaving aside the premium I'd pay for in stock items like this.

They also gave me good advice on other stuff, they clearly know what they are talking about.

It's a big thumbs up from me for Norris's in Isleworth

 

[rosssavage]

Said it on this forum sooo many times in the past: avoid steel developments and go to Norris first every time!!

SD just want to sell you stuff, Norris will actually repair / manufacture stuff.

 

[Elessar]

Said it on this forum sooo many times in the past: avoid steel developments and go to Norris first every time!!

SD just want to sell you stuff, Norris will actually repair / manufacture stuff.

I think that's a little harsh, I have always had good repair service from SD. They reckon they make more from repairs than sales actually. But norris's did impress me.

 

[rosssavage]

I think that's a little harsh, I have always had good repair service from SD. They reckon they make more from repairs than sales actually. But norris's did impress me.

And of course each to their own. I may have been unlucky, but in my personal experience SD were dismissive and disinterested in anything other than selling me a new prop as mine was 'beyond repair'

Norris managed to repair it and I'm still using it eight years later!

Tbh SD do seem to have a good reputation, but Norris have always got it spot on with me from my first dealings with them, and friends I have recommended them to have also experienced nothing but under promising and over delivering with both quality of work and turnround time.

Pleased you got it sorted either way

 

[rafiki_]

I think that's a little harsh, I have always had good repair service from SD. They reckon they make more from repairs than sales actually. But norris's did impress me.

A+1 for Steel Dev. Have used them many times, and always impressed. They have repaired a prop for me that I thought was a gonna. Price and service top notch too.