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Bow thruster weed hatch


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We didn't do enough research when we bought our boat and simply asked the maker to include the tube. He added a weed hatch as well - sorry the boat's 20 miles away so I can't take a picture just now.

 

The weed hatch is to one side of the centre line of the boat.

 

Have just had a Side Power bow thruster fitted - which we hope to connect up this weekend - and that's on the centre line of the boat. However, the boat had to come out of water to fit the thruster as the tube is below water level (not surprisingly). Also, and probably more importantly, the thruster has two props, and only one can be accessed from the weed hatch.

 

I'm told that some BT's and, I presume, props, will lift in and out without taking the boat out of the water.

 

What we now recognise as the weedhatch was initially thought by me to be where the thruster was mounted.

 

If I was doing it again - no chance - I'd have a weedhatch style structure in the middle of the boat big enough for the thruster and a supporting plate shaped to the curvature of the tube could be easily removed if needs be.

 

Although I can get to one prop from the weedhatch I need to have the boat out of the water to get to the other one. I'm just hoping that the grills at the end of the tube will keep anything really damaging out of the tube and the prop will survive.

 

Not exactly what you asked / wanted, but I hope it helps.

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We are looking to build a weed hatch onto our bow thruster tube, (Vetus 55kgf thruster)

Would appreciate any photos, any tips how best to fabricate and make watertight

thanks

 

It really depends on what sort or boat you have.

 

If it's a narrowboat or NB style widebeam you may have the problem that to get the top of the hatch above the waterline it has to come right up close to the bow deck - too close to get your arm in. In that case you could incorprate it into the deck and have a flush screw down cover on top - similar to an integral water tank cover. The problem then is that the hatch may be too long for you to get your arm down and your hand round to the prop!

 

Some NBs have the thruster tunnel in the bow locker (and have gas locker elsewhere), so then you wouldn't have this issue.

 

The BT on my widebeam is mounted about 18" from one side and there is no weedhatch. The prop has never been fouled but if it does then I'll have to get in the water to clear it. Not a pleasant task :huh:

 

If yours is a narrowboat then I'd have thought you should be able to reach the prop from either side.

Edited by blackrose
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Thanks to all for their help.

 

The boat is a small (40' x 10') replica dutch barge type and the bow thruster prop would normally be inaccessible without going in the water.

 

The bow thruster is quite small only a 6" tube (arguably too small though I believe dhutch uses the same size on a heavier longer boat)

 

Hence a weedhatch modelled along same lines as the one on the main engine is proposed, but it would be deep to get it 6" above waterline and very narrow because of the tube, I was therefore looking for any one who had drawings/photos showing how this had been achieved and comments on results. I realise that I would not be able to remove the leg this way but need to reach the prop to clear and perhaps if need be remove prop up through the hatch

 

The idea of lifting out a plate with the whole unit attached is the best (I think) though could be thwarted by a long stick jamming the prop and stopping it lifting. Some bowthrusters (but not ours) are actually designed with this in mind and come with the plate and sealing. On this type of weedhatch the bottom plate which is always under water would need a good seal wheras on the former type only the top plate which is above water and only subject to splashing needs to seal. Therefore I doubt our engineering ablility to fabricate such a bottom plate and watertight seal, but if anyone has done it that would be very interesting to see.

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The BT on my widebeam is mounted about 18" from one side and there is no weedhatch. The prop has never been fouled but if it does then I'll have to get in the water to clear it. Not a pleasant task :huh:

do you have trash grid bars fitted to the openings, Mike?

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We dont have a weedhatch, or any form of coffer dam, around our vetus bow prop. A 1991 3kilowatt unit, the predecesor of the 55kgf model i beleave.

- Its mounted centrally, with four bars welded over the end of the tube to stop big stuff geting in.

 

You can have a weedhatch, and the vetus only has the one prop, and you can/should also mount it a bit off center if you have a longer tube than we have.

- The other way it to have it a locker, or the otherside of a full height bulkhead or simular. Or to have it affectly mounted down a tube coming off the bow tube itself. So it basically is the weed hatch.

 

However at the same time, ours has done 17years of (admitadly light) operation. And the only problem we had with it was a year ago when the attachment for the anode came loose, which as its thoughtlessly tapped into the main casing with a non-blind hole, caused the unit to not hold oil anymore.

- We thought its seals had failed, but when next in drydock it turned out they where fine, the hold pluged (without anode) and the unit cleaned and reassembled with new seals and batterys replaced.

 

 

The only problem we did have, was when it was very first fitted carlessly, causing the prop to come loose.

- This was sorted by draging the bow up a bank with a excavator a bit, and geting in with wellys on and doing the job.

 

 

Daniel

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do you have trash grid bars fitted to the openings, Mike?

 

Yes, but just 2 vertical bars and 1 horizontal, so I can still get my forearm through. According to Vetus, too many grid bars will reduce BT efficiency.

 

The thing is if the prop does get fouled and you have no weedhatch, you just carry on without the BT until you find somewhere where you can get the bow by a sloping bank so you can safetly get into the water.

Edited by blackrose
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