Likely boat speed ? Suggestions.

[PGD]

Right then boffins something for the little grey cells this morning.

Need to try an get an estimate on likely speed at sea of boat given the following information :

Got a Fairline Holiday with Volvo AD31P 150 hp turbo diesel engine and a DP-e drive with A5 props on her. Max revs 3900. Weight wet 2.25 tonnes.

Tank capacity 50 gal

Consumption – river use 2 ltr / hr at 1200 rpm – known fact.

Volvo consumption figures :

Cruising 16 ltr / hr = 3.5 gal/hr and 10 hrs running time

Max load 27 ltr / hr = 6 gal/hr and 6 hrs running time

This assumes 30% safety factor so worked on 35 gals of fuel available.


I know there are other factors to consider but any suggestions would help.

Cheers

Peter

 

[maxtorque]

Dependant on your hull profile, trim and C of G: 25 -28kts (2 on board)

WT

 

[tico]

I would guess thats about spot on.
Very dependant on Hull cleanliness and trim attitude

 

[PGD]

cheers for the info - hull is semi plaining - v at the front flattening out midships - to the rear. small keel - no more that 6".

DP-E drive has trim also have trim tabs fitted - hull has erroding antifoul so should be clean by the time we get to open her up proper like

PS is it woth changing my anodes for a couple of weeks as a salty sea dog?

Peter

 

[tico]

Try different hull trim.... tabs. Slightly bow up should give better speed but not so soft ride.



Been there, done that, got the oily T shirt

 

[PGD]

will have to play when I get to sea - stuck on the Thames so can't do anymore than 4/5 kts. Will remeber advice

cheers

 

[BarryH]

I was on the Thames the other day. Theres no set limit below wandworth bridge, but bylaws state " proceed at a speed blah, blah wash, blah blah, and so on! Port O london chappies slapped my wristies for going a bit too rapid. Also don't forget to contact woolwich radio or whoever it is about going thruough the barrier. They got some work going on between a couple of bridges as well. Might be worth giving the authority a call, Case of granny and eggs me thinks

OK, to hell with it. Unbolt it and we'll use it as an anchor!

 

[PGD]

was aware but cheers anyway - don't you have to caal a n other radio on entering tideway just to say i'm here? - knew about the barrier bit. Do you think POL will give me permission to "Engine Test" ?

 

[BarryH]

Well the bylaws say " proceed at speed that does not endanger other people, vessels,property" Or somthing like that. So if your on an empty stretch below wandswoth, err... go for it. Most of the other boats, especially the commercial operaters, don't seem to stick to any sort of limit. I think you can pick up a copy of the PLA bylaws at Teddington lock anyway. The web site is quiet good for info as well.

OK, to hell with it. Unbolt it and we'll use it as an anchor!

 

[PGD]

yup you're right - safe speed etc.

will probably drop down a bit below wandsworth and boot back up river - that way I get a look see for logs etc

 

[duncan]

never known a thames boat that hasn't aquired another ton of goodies hidden in every available space......probably find you are a little over the 2250 kg mark initially!
Antifouling, even eroding, will need a light brush rather than just water travelling past @ 20+ knots to 'clean up' if it is at all fouled - sad but true.
ps Kitchen sinks can make excellen anchors though.

 

[PGD]

hi, - the 2.25 came from a slight over estimate to calculate the props when she was re-engined. Dry weight from orignail build is 1850 kg so allowing for kit , crew, water, fuel etc that seemed a good number to go for. So she shouldn't be far off that.

peter

 

[aztec]

go on then try this one... old bucket of nuts, bolts and spiders (bloody big un' and all) twin ford diesels 55hp? each. 14x11 props@ 3000rpm. 2.5-3 tons old money. what would i be looking to get cruising?

you can see the 'orrible thing below.

cheers, steve.

<A target="_blank" HREF=http://homepage.ntlworld.com/s.amos/index.html>http://homepage.ntlworld.com/s.amos/index.html</A>

 

[Chris_d]

Re: Beware

The manufactures quoted weight for my 224 was similar at 1795kg, actual weight
on weighbridge excluding trailer (some fuel and water) 2697kg!!!
Depends what day of the week your hull was laid up and how much resin they slapped on, then the hull will have absorbed moisture over the years etc etc..

 

[PGD]

Re: Beware

fair comment sir - i'll get my spring balance out but the advice above checks out with whatmy engineers estimaed so maybe it's not that far out.

We'll se when I get her to sea.

cheers

peter