Help needed re - Boat Draught

[NomadicDilligaf]

We are looking at buying a 57 ft narrow boat and the previous survey says the draught is approx 2ft 8'. From reading on the forum and asking around this seems pretty deep. Should this be a concern and enough to walk away?

-We would like to cruise as much as possible, could finding moorings be a challenge to find with a draught this deep?

-The boat builder spec claims its 26 inches and from the picture of the boat it does look like the bow sits higher out of the water leading me to believe the stern is over weighted from the engine, batteries, washing machine etc Would adding more ballast to the bow area help fix the overall draught as the brokerage claims its just the skeg creating the deep draught?

 

Advice & help is much appreciated. Thanks 

[Tony Brooks]

Others cruise extensively with deeper draft boats, but may have to slow down on narrow canals.

 

Most narrowboats trim down by the stern, this affects the pivot point when turning, so trimming it level may well alter how it handles.

 

Is the water tank full, that often pushes the bow down by about 2", no idea how it affects the stern though.

 

It may be better to remove ballast from the stern end, and there might be trimming ballast around the engine (if the engine is at the stern).

 

 

 

[blackrose]

2ft 8in is 6 inches deeper draughted than my widebeam but it doesn't sound that deep to me. Yes I daresay if you fill the water tank (assuming it's at the bow) and reballast you could get it sitting flatter in the water, however you need to make sure the sterngear and uxter plates don't come up too much.

[nicknorman]

Our boat is 2’8” and I like it. There are + and - points, the main plus is that it doesn’t skitter sideways in strong winds compared to shallower boats, and it can swing a big prop which is more efficient.

 

minus points are of course that it tends to ground more easily, but we don’t find that a significant problem. Probably the biggest issue would be the Llangollen above Trevor, but we still managed it (with some difficulty).

 

You can easily check the draft by opening the weed hatch and putting a steel tape measure down to hook under the skeg, and reading off at the top of the water.

 

To check if the boat is properly ballasted, look at how far submerged the back corner is (the counter). It should be a couple of inches below the water. If it is less, air will be sucked in in reverse and the boat will be harder to stop. If much more, this creates extra drag and means that hull fittings (exhaust, ventilation etc) might be closer to the waterline than the designer intended.

[Jen-in-Wellies]

Think of owning a deep draft boat as a public service to boaters. Ploughing a deep channel through the mud and shopping trolleys for others to follow. 😀

We salute you!

[Jon57]

6 minutes ago, Jen-in-Wellies said:

Think of owning a deep draft boat as a public service to boaters. Ploughing a deep channel through the mud and shopping trolleys for others to follow. 😀

We salute you!

Yep. We should get a 10% reduction in our licence fee for the good work we do for our fellow boaters. Happy day's 😁👍

[BoatinglifeupNorth]

Who is the builder? As most builders boats are roughly the same and the builder states 26” now it’s 32” has it been re-plated in any part? As to drop down 6” could effect outlets including the exhaust. Maybe ask the previous owners who had the survey done if they know. Fill the water tank and try to measure it.?

[BEngo]

2ft 8 in of draft is not really a problem on most canals.  We run around at that or more.  You may find the skeg bounces over a few things, especially the back blocks of the BCN.  You will also sink a bit further when going along.

However, if the swim is 2ft 2 deep, as spec, then the stern is over ballasted, by about 5 inches.  The counter should just sit in the water, enough so that waves cannot make annoying slop slop noises at night.   First thing is to get out as much stuff as possible from the engine bay. Ditch or shift forward any easily accessible ballast from the middle back.  Loading the bow will also help- fill the water tank as suggested, and add ballast.  Every inch down at he bow will raise the stern about 1/2 an inch. Don't get nose down though.!

 

N

 

 

 

[agg221]

We draw 3'1" static, so a bit more when moving. We made it to the end of the Llangollen and the BCN isn't really too much of a challenge, except that we do pick more rubbish. We hit the odd thing underwater but the only two places we have got really stuck in the channel are the narrows before Titford Pools (gave up on that one) and the last lock on the Llangollen which has a major scour below it at the moment. Generally it is not an issue.

 

I think the only place which might really be a problem is Savick Brook on the Ribble Link. Not sure we would clear that, although we do have very low air draught (Dudley Tunnel low) so I wonder if we could make it under the bridge while the water is still high enough. At 2'8" you should have no problems.

 

Alec

[MtB]

43 minutes ago, BoatinglifeupNorth said:

Who is the builder? As most builders boats are roughly the same and the builder states 26” now it’s 32” has it been re-plated in any part?

 

I was wondering the same.

 

To get the stern of a 57ft boat 6" deeper in the water than the builder says it should be would take a couple of tonnes of unexpected extra weight in the back at least. I think the OP should definitely be asking more questions about how this came about. 

[Tony Brooks]

I wonder if the OP has checked the cabin bilge for water.

[BoatinglifeupNorth]

16 minutes ago, Tony Brooks said:

I wonder if the OP has checked the cabin bilge for water.

What’s more important is, if it’s full of water, why wasn’t it picked up by the Surveyor who wrote the last survey report saying the draft had increased by 6” from the builders build specification.

Edited December 24, 2023 by BoatinglifeupNorth

[NomadicDilligaf]

Thanks for all the advice guys! Much appreciated! Feeling more relaxed about the draught depth now.

My initial concerns have pretty much been overcome, I was concerned about cruising and finding moorings with its draught. I've now booked a full survey to check the boat further. Once I've had the survey done I'll update the thread with the results in regards to why the draught is deeper than the boat builders claims, if indeed it is.

[magnetman]

There could be a lowered skeg. Not very likely to account for 6 inches extra draught though to be fair. 

 

It depends how the draught has been measured. Waterline to bottom of skeg or waterline to base plate. And was the waterline wet or was it estimated with Boat out of water. 

 

 

 

And of course has it been overplated. 

[IanD]

3 hours ago, Tony Brooks said:

Others cruise extensively with deeper draft boats, but may have to slow down on narrow canals.

 

Most narrowboats trim down by the stern, this affects the pivot point when turning, so trimming it level may well alter how it handles.

 

Is the water tank full, that often pushes the bow down by about 2", no idea how it affects the stern though.

 

It may be better to remove ballast from the stern end, and there might be trimming ballast around the engine (if the engine is at the stern).

 

 

Adding ballast to the bows to bring the stern up isn't very effective, it's far better to lighten the stern -- I know, I went through this exact process when my boat was put into the water and the stern was low and the bow was high. Roughly speaking, a ton of ballast in the middle of the boat will drop the whole boat about 3cm in the water, if you put it right in the bows then they'll drop about twice as much as the stern comes up. 6 inches extra draft means the boat is about 5 tons heavier than it should be, if this is the extra depth everywhere -- no way can shifting ballast correct for this.

[GUMPY]

Loddon had four inches of water in the cabin bilge when I bought it. As there was no underfloor access it was missed by both me and the surveyor. Only discovered because immediately after survey we moved the boat 60 miles by road and a wet patch appeared from the sloshing water on the opposite side to any plumbing.  

Pumped it dry and never found the cause however it was dry for the next ten years 

[magnetman]

Yes I think the rule of thumb for working narrow Boats was one ton per inch immersion. 

 

So if it was a 60ft that would be 70/60 inches per ton. Assuming the weight is central overall. 

 

Approximately. 

 

 

Edited December 24, 2023 by magnetman
corection

[IanD]

3 hours ago, magnetman said:

Yes I think the rule of thumb for working narrow Boats was one ton per inch immersion. 

 

So if it was a 60ft that would be 70/60 inches per ton. Assuming the weight is central overall. 

 

Approximately. 

 

 

Will that be about 3cm then? 😉

[magnetman]

Yes. That's why I started my post with the word 'yes'. I was agreeing. 

[Wanderer Vagabond]

8 hours ago, agg221 said:

 

 

......I think the only place which might really be a problem is Savick Brook on the Ribble Link. Not sure we would clear that, although we do have very low air draught (Dudley Tunnel low) so I wonder if we could make it under the bridge while the water is still high enough. At 2'8" you should have no problems.

 

Alec

If you decide to do the Ribble Link, as I commented on another thread, a good option would be to go up to Preston Docks for the night and then come back on the ebbing tide the following day. It means you pass over the tidal gate at pretty much full tide (only takes about 30 minutes from Preston to Savick with the tide) so grounding is far less of a concern than if you've come from Tarleton.

[manxmike]

Could it be a heavily overweight person on the stern deck when the measurements were taken? Given the trend seems to be for people to be enormous perhaps taking most of the ballast out would be a good idea.

I remember (in my youth, when dinosaurs roamed freely) that on some commercial flights passengers had to be weighed and then told where they could sit to balance the aircraft - maybe something similar needs to happen with this narrowboat?

[ditchcrawler]

31 minutes ago, manxmike said:

Could it be a heavily overweight person on the stern deck when the measurements were taken? Given the trend seems to be for people to be enormous perhaps taking most of the ballast out would be a good idea.

I remember (in my youth, when dinosaurs roamed freely) that on some commercial flights passengers had to be weighed and then told where they could sit to balance the aircraft - maybe something similar needs to happen with this narrowboat?

We were weighed before flying out to Offshore platforms as was all baggage 

[nicknorman]

8 minutes ago, ditchcrawler said:

We were weighed before flying out to Offshore platforms as was all baggage 

 

And then you were weighed before flying back home again just to check how much weight you had put on whilst offshore!

[ditchcrawler]

Just now, nicknorman said:

 

And then you were weighed before flying back home again just to check how much weight you had put on whilst offshore!

Not as much as the air crew put on when they were fed by more than one platform on a trip

[jonathanA]

presumably the survey scared the OP off as he's not been back for two months...