FWB
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if a 22ft boat displaced 4 tonnes i doubt it would float
My 28ft boat is 8.5 tons. It's been afloat for ten years now.
How heavy is a Hillyard 4 tonner?
- Thread starter ghostlymoron
- Start date
My 28ft boat is 8.5 tons. It's been afloat for ten years now.
sailorman
Well-Known Member
& probably a canoe sternTranona
Well-Known Member
My 37' boat is just under 6 tons, but comes out at over 11 tons with your "formula" - which suggests it is of little use as a general formula.
FWB
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Is she a long keeler? It's just something I found on the web which works very well for my long keeler.
sailorman
Well-Known Member
much the same weight as our 37 footer
Tranona
Well-Known Member
Yes, it "works" for your boat, but is not a general formula - even for long keel boats. Just have a look at waterline/displacement ratios and you will no doubt find your boat is at the heavy end of heavy which is why it is twice the weight of boats of similar length but lighter displacement shapes.
It would only transfer to the Hillyard if the L/B ratio and WL/Disp ratio were the same as your boat.
FWB
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It would be interesting if other owners of long keeled boats could try it out.
I've been looking through my vast pile of Classic Boat mags for an article on this subject which gave a very good formula, but have yet to find it.
It can't work for all boats but its supposed to be good for old style long keeled boats.
I'm not pretending that its perfect, just trying to help the OP.
I've been looking through my vast pile of Classic Boat mags for an article on this subject which gave a very good formula, but have yet to find it.
It can't work for all boats but its supposed to be good for old style long keeled boats.
I'm not pretending that its perfect, just trying to help the OP.
FWB
N/A
Yes they are similar 3.3 and 3.5 for LWL/WLbeam
TimBennet
Well-Known Member
Well, one estimation of the displacement in Long Tons (2240lbs) is that it is equal to one hundreth of the LWL (in feet) raised to the third power multiplied by the Displacement Length Ratio.
The DLR is dependent on the 'hull form', but consisitent for all boat sizes. For a Hillyard we could hazard a guess that a DLR of around 350 would be appropriate.
Therfore, assuming also a WLL of 20ft, (90% of LOA was often used) we get a displacement of 2.8 long tons or 6300 lbs.
If the DLL was 400 (very high) , we would get 3.2 tons.
Going to the low end of the range (and I think a bit beyond!) for such a hull form, we could use a DLR of 320 and then get 2.6 tons.
ghostlymoron
Well-Known Member
I guess when Hillyard produced his boats he didn't know how heavy they'd be until they were finished.
Looking through my 'Cruising under sail' there are several examples:-
Mercy Jane LOA 40', LWL 27'6", beam 9' displacement 9.5T, T.M 12T TM/disp 1.26
Restive LOA 30' 7", LWL 22', beam 8'3", displacement 4.7T, TM 6.8T TM/disp 1.44
Englyn LOA 26'6", LWL 22'6" beam 8'7", displacement not stated, TM 7T
Amokura LOA 50'9", LWL 38', beam 12', displacement not stated, TM 28T
Comparing with Restive, the Hillyard is quite heavy (or short)
Looking through my 'Cruising under sail' there are several examples:-
Mercy Jane LOA 40', LWL 27'6", beam 9' displacement 9.5T, T.M 12T TM/disp 1.26
Restive LOA 30' 7", LWL 22', beam 8'3", displacement 4.7T, TM 6.8T TM/disp 1.44
Englyn LOA 26'6", LWL 22'6" beam 8'7", displacement not stated, TM 7T
Amokura LOA 50'9", LWL 38', beam 12', displacement not stated, TM 28T
Comparing with Restive, the Hillyard is quite heavy (or short)
Tranona
Well-Known Member
But it is the WL/Disp ratio that is important. Your boat has a very full hull with a high prismatic coefficient so it needs the weight/displacement to sink it to its LWL. You can have long keel boats with light displacement, for example 1950's and 60's racing boats from Giles, Holman, S&S etc.
FWB
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Basically if you imagined the Hillyard's underwater shape to be oblong it has a volume equivalent to about 16 tonnes. You just have to imagine how much of the oblong is cut away to leave the final shape. That's what the formula is trying to figure out. I don't know the answer but it's probably no more than 75% removed, leaving about 4 tons.
Anyway it looks like a nice seaworthy boat and it floats. It won't bang in a seaway but may cause angst when put astern in a confined space!
Tranona
Well-Known Member
Yes, it is a heavy displacement hull shape, but would suggest not as "heavy" as yours. Seriously doubt it would be much above 3 tons (either metric or imperial).
BTW the ratio you are looking for is the one I referred to - the prismatic co-efficient. That is the proportion of the "box" the hull fills. Used to be able to work it out but brain has gone all rusty through lack of use, - you will find it in Skenes or Dixon Kemp (the formula that is, not my rusty brain).
BTW the ratio you are looking for is the one I referred to - the prismatic co-efficient. That is the proportion of the "box" the hull fills. Used to be able to work it out but brain has gone all rusty through lack of use, - you will find it in Skenes or Dixon Kemp (the formula that is, not my rusty brain).
FWB
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Well you may be right, I'm just trying to figure a way of guessing the displacement.
For comparison here is the Hillyard
And here is my Heard28
For comparison here is the Hillyard
And here is my Heard28
TimBennet
Well-Known Member
Well, as I said a couple of pages ago, the traditional way is to use the LWL and the Displacement Length Ratio. This dimensionless 'ratio' is consistent across all sizes of boats and indicates (as the name would suggest) the volume (displacement) or size of the underwater part of the vessel per unit of waterline length. Big, chunky, high volume boats have a high DLR. Then if you know the LWL you can work out the displacement.
The only displacement I can find quoted for the Heard 28 is 8.5T. This would give a DLR of 456 which is high, but could well be right looking at your photo.
Harrison Butler was heavily influenced by the Falmouth Quay Punt, and Ian Howlett says HB's Yonne design, (LOA 26ft, LWL 22.5, TM 6.5T) has a DLR of 480, so we are in the right ball park.
Now for the Hillyard, if we assume it's (by the looks) no chunkier than the Heard and could well be less chunky, then it's not unacceptable to consider the DLR range to be 450 at the top end and 380 at the (very) low end. As the transom looks quite raked the LWL could be 19ft 8 inches or so). Therefore . . .
. . . as D(Long Tons)= (.01xLWL)^3 x DLR we get a range for its displacement of 2.9 to 3.4 tons.
FWB
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Thanks Tim, looks about the right range.
Gordonmc
Well-Known Member
My previous boat was a Hillyard 8 Tonner.
That is, both the Thames Measurement and Hillyard Measurement were 8 tons.
However, according to the carving in one of the beams it was 6 3/4 tons.
I always assumed that was displacement.
That is, both the Thames Measurement and Hillyard Measurement were 8 tons.
However, according to the carving in one of the beams it was 6 3/4 tons.
I always assumed that was displacement.
sailorman
Well-Known Member
where is the Flap now
TimBennet
Well-Known Member
That's more likely to be its registered tonnage as carving beams was done as part of the Pt Registration process.
Tranona
Well-Known Member
No, that is the registered tonnage, which is a measure of carrying capacity, calculated by the measurement surveyor. Origins are as a basis for levying port and light dues. You will find the actual calculation on the original registration document AKA Blue Book. This measure can vary, even between two boats of similar design depending on the way the "allowances" - for example for chart space and machinery space are calculated. Clearly there is an incentive to maximise allowances to minimise charges - although this is irrelevant for pleasure boats which have been exempt from such charges for years.
