stern tube glassed in at almost max angle

[bajo]

stern tube was set up to be glassed in at 10 degs.but it must have shifted during glassing in and (and lots of glass), now it is 14.5degs . impossible to do anything about it now. The manufactures yanmar 1gm10 max angle is 15deg. I am extreemly upset and worried about it.The boat is 22ft sailboat

 

[30boat]

Yes,that's a problem.One way around it is to fit an Aquadrive.It's expensive but it has the added benefit of taking the considerable motion of the Yanmar engine at tickover and alignment issues will be a thing of the past.Main problem aside from cost is that it adds around 22cm to the engine length.

 

[misterg]

stern tube was set up to be glassed in at 10 degs.but it must have shifted during glassing in and (and lots of glass), now it is 14.5degs . impossible to do anything about it now. The manufactures yanmar 1gm10 max angle is 15deg. I am extreemly upset and worried about it.The boat is 22ft sailboat

Chop it out and start again.

- your engine will be very high, otherwise.

0.02p

Andy

 

[vyv_cox]

Chop it out and start again.
Andy

I agree. Chopping it out is largely a matter of time and effort, not lots of money. Take it out and start again. Next time, set it up with simple jigs made of timber or something easy, so the tube cannot shift. It's worth taking it slowly, make up some epoxy putty and pin the tube in position before trying to do heavier work such as stippling glass around it.

 

[bajo]

If i can cope with the engine being higher can the stern tube angle be left as it is?

 

[misterg]

If i can cope with the engine being higher can the stern tube angle be left as it is?

It's your call, but leaving it as it is puts you right on the manufacturer's limit for the engine (presumably against the static water line with no allowance for the boat squatting under power, or pitching, etc.); Puts the centre of gravity of the engine much higher than it needs to be so the boat would be a bit more tender than it should be - I would guess that the engine weighs >50% of your keel(s)/ballast??; and makes it a non-standard installation if this is important to you. What are the implications for the 'P' bracket, prop & rudder?

If I was in your position, I know I would be looking for all sorts of alternatives to avoid having to re-do the stern tube, but in truth (IMHO), the right thing to do is to chop it out and re-set it. It may seem daunting, but in the scheme of things, you're looking at a bit of mess, some more glass / resin and a day or two's work. If someone else has done it wrong, ask them to put it right.

I think that if you go down the road of leaving it as it is you'll probably come across more and more un-anticipated problems further down the line.

Only my 0.02p, but I think you'll regret it if you don't bite the bullet and put it right now.

Andy

 

[Baggins.]

Chop it out and start again.

- your engine will be very high, otherwise.

0.02p

Andy

Agree, we all make mistakes and it seems Alot of effort to fix it now but it spares a potentionally large job In the future and the headache of having to manouvere with it at that angle.

 

[DownWest]

Get a Starrett Hole cutter a few sizes larger than the tube. Slice the back off and weld the rest to a steel tube of the same dia. long enough to cut through the glass. Weld the back of the cutter onto the end, or arrange a mandrill for a slow speed drill. This gives you a very long hole cutter for little cost.
In my experience allowing errors to stay will bite you later. A Halyard drive would sort the angle problem, but ,as said, the extra length might be a prob in a 22ft. Apart from the extra cost.
A

 

[wotayottie]

leaving aside any waves etc, the angle of the tube to the horizontal will vary by a few degrees simply as you walk to the bow or bback to the stern

sure its a PITA to rip it all out but much the best thing to do. next time fabricate some plywood webs for the inner end of the tube as well as the bit where it goes through the hull and glass them in with just a layer of epoxy and webbing. once cured you can check dimensions and if they are ok you can then add the re-inforcement layers. dont do everything at once.

 

[bajo]

At the moment looking at getting an aquadive ,its more than difficult to cut out the tube .hang in there for me!!

 

[vyv_cox]

At the moment looking at getting an aquadive ,its more than difficult to cut out the tube .hang in there for me!!

If I remember correctly, Aquadrive will only accept a maximum of two degrees anyway. So you won't be a lot better off and having installed an Aquadrive myself, I can advise that it is considerably more technical and time-consuming to do than replacing a stern tube. Not to mention the cost, which will be considerable.

You asked for our advice and have been given plenty. I can only suggest you follow it. The extended hole-cutter suggestion is a good one and would not be too expensive to have done if you can't weld yourself.

 

[npf1]

Just a thought ... mght be worth considering hiring a construction site type concrete core cutter.

 

[fergie_mac66]

well the prop will waste power pointing down.If you strain the alinement you will get vibration.
you will probably wake up in the middle of the night every so often, thinking "I wish I had put it right when I had the chance"

To conclude why spoil the ship for an 'apeth of tar

 

[noelex]

Given the considerable difficulties changing the prop shaft angle, personally I would leave it as is. You are within the manufactures specs for the static inclination which should allow for pitching during operation. (otherwise everyone would be in trouble)

 

[Bajansailor]

Here are a few photos for reference of the work carried out so far on the engine beds and installation of the GRP stern tube on David's Galion.

Here she is at her mooring in Carlisle Bay, with O/B engine

A view looking aft under the cockpit on the new glassed in stern tube. A cutless bearing has been fitted on the inboard end of the stern tube.

And the stern tube from the outside - the cutless bearing has not been fixed in place, and the temporary shaft is a 1" diameter thin wall S/S tube.

It looks like it will be quite a major job to cut out the GRP stern tube - a lot of resin and mat has been lavished on it already.

Here is a plan view on the new beds

Here is a closer view of the new beds, with a scale for reference - the flanged GRP brackets (for the forward mounts) are approx 8.5" long. The beds for the aft mounts are just built up layers of fibreglass - the laminator who laid them up was of the opinion that the mounts could be fastened to these GRP beds using lag bolts, however I think that something like a home-made Bighead fastener would be better.

And here is the new Yanmar engine, complete with new Vetus Bullflex coupling

Here is some info re these couplings from the Vetus catalogue - http://viewer.zmags.com/showmag.php?mid=hggds#/page186/
They note that these Bullflex couplings can cope with a miss-alignment of up to 2 degrees.

David has a Volvo shaft seal which he plans to install - however I am wondering if the cutless bearings inside the stern tube (especially the forward bearing) might not get too hot, as there will not be a steady supply of cooling water flowing over them - only water that seeps in slowly from outside.

We were discussing the possibility of fitting a Halyard Marine Aquadrive unit instead of the Bullflex coupling. The mounts on the engine are fairly flexible, and I am wondering if the shaft (held rigidly in the cutless bearings) will cope with the vibration from a single cylinder engine, even with the Bullflex coupling in between (?).
There is enough room to fit an Aquadrive unit - but they are around GBP 450, hence a significant extra expense.

Davis has also purchased a Vetus muffler and a gooseneck for the exhaust, and is thinking that he should also install an anti-syphon valve. The slope from the standard exhaust elbow to the muffler box is rather shallow (the box will sit in the 'vee' of the hull, above the GRP stern tube), hence I am thinking it might also be prudent to have a S/S 'high rise' exhaust elbow fabricated (?)

What are the panel's thoughts re the above installation so far?

 

[misterg]

Have the engine beds been put in to the 10° shaft angle or the ~15° shaft angle?

Will the engine physically fit at a 10° angle? - It looks tight if the mounts in the photos are set to suit 15°

Where did the 10° figure come from?

Andy

 

[Thistle]

If it were my boat and it was left like this, I would probably always be on edge wondering if it was going to fail. It's a pain to fix it now but I think I would still do it for future peace of mind.

£.02

 

[Blueboatman]

Another 2p worth ( they all add up)

Electric Jigsaw, hardpoint handsaw, 4 inch grinder...(and rubber gloves and mebbe a trickle of water to keep the dust down, yes I know its 110v out there)..

Remove it, temporarily mount the engine as you would like it, and bolt on the new propshaft assembly and tube complete, then 'set' the repositioned tube with fibreglass paste, slide engine to front of cabin and laminate over the existing laminate and correctly sited tube to permanently bond it in correct position..

This way you can optimise where you want the prop to be, and get the engine as low and flat as practicable without having to do it all from measurement and plans and braces and angle dangles..

 

[vyv_cox]

.

David has a Volvo shaft seal which he plans to install - however I am wondering if the cutless bearings inside the stern tube (especially the forward bearing) might not get too hot, as there will not be a steady supply of cooling water flowing over them - only water that seeps in slowly from outside.

We were discussing the possibility of fitting a Halyard Marine Aquadrive unit instead of the Bullflex coupling. The mounts on the engine are fairly flexible, and I am wondering if the shaft (held rigidly in the cutless bearings) will cope with the vibration from a single cylinder engine, even with the Bullflex coupling in between (?).
There is enough room to fit an Aquadrive unit - but they are around GBP 450, hence a significant extra expense.

Davis has also purchased a Vetus muffler and a gooseneck for the exhaust, and is thinking that he should also install an anti-syphon valve. The slope from the standard exhaust elbow to the muffler box is rather shallow (the box will sit in the 'vee' of the hull, above the GRP stern tube), hence I am thinking it might also be prudent to have a S/S 'high rise' exhaust elbow fabricated (?)

What are the panel's thoughts re the above installation so far?

I have no experience with this type of installation but I suspect that a Cutless rubber bearing could not cope with conditions on the inboard end of the tube. It is normal to leave a clearance of at least 6 mm between prop, anode or whatever and the cutless bearing to ensure sufficient water flow. At the very least I think you need a vent inside the boat to avoid airlocks at the inboard end. My PSS seal requires this for the same reason.

I'm also not sure that a Bullflex will cope with the engine movement, but maybe someone with some experience of it will know. An Aquadrive will certainly do the job, and will mean that there is no need for the inboard cutless bearing. However, some skill is needed to measure up, cut and fit the mounting plate, it is not simply a matter of replacing the Bullflex.

The job seems to have been done well, pity about the alignment though. My preference would be to cut it out and replace at the correct angle, which actually doesn't look too difficult a job. Someone else suggested a concrete borer, which was an idea that occurred to me overnight. Using the stern tube as a guide it wouldn't need the pilot drill, and would probably only need to go a few inches to be inside the boat. It appears that the internal glass could be ground out fairly easily. A PITA, I know, but with the engine on its mountings it would be easy to get the alignment right the second time.

 

[30boat]

FWIW the Aquadrive coupling will cope with a lot more than 2º.More like 8º.