Tarquin Trader

[Newbroom]

At last a subject I have some knowledge of.
Traders being semi displacement do tend to roll at less than 12 knots so do planing hulls so do displacement boats. They are also extremley wet boats so are Nelsons so are Aqau Stars. Its the hull design of a semi displacement boat.
Fuel consuption is a variable figure but they are less economical than a planing hull at speed.
At 10 knots I used to do Channel Isle to Gibratlar non stop 104 hours on average and burnt a gallon a mile. At 20 knots I probably would not of made Royan.
Technically at 7 knots I had over 2000 miles range. that was with the additional tanks I had fitted from new. 1000 gall capacity.
The difference between a 575 and a 535 is not 4ft as you might expect but is only 2 ft due to the way the boats are measured.
The build quality over the years has improved no end. The value for money £ for £ feet LOA over its rivals makes it hard to justify a different boat in the same class.
I have owned three Traders during my boating career and delivered many more some of them in horrendous conditions across the bay and while I would be the first to say that they might not be perfect they are an excellant sea boat with now a good build quality and one of the few affordable long distance cruising motor boats available to day.
Would I buy another one I hope to place an order shortly for a 505 (which is only 4 ft shorter than my previous 575)
I too like the Atlantic 50 but again what a price difference.
Gludy i will pm you with my telephone number and i will be pleased to talk to you about my experiences

Dave

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[Gludy]

I am not as experienced as you on this subject but I agree with every word you have said.
Please PM me.

<hr width=100% size=1>Paul

 

[kimhollamby]

I agree...

...in fact the Squadron might in fact be less expensive to run at displacement speed given it is dragging less hull through the water...not a slight on any boat, just a general hydrodynamic observation.

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[camargue]

what about...

what about an Ocean Alexander? almost brought a 52 pilothouse a few years ago.these too are semi displacement. not sure about fuel consumption, but was very good at sea, with a top speed of 22-23 knots.

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[Gludy]

Re: I agree...

Butyou are missing the point Kim.

First of all the ride at displacement speed with a planing hull is not good. Secondly you cannot say go at 13 knots, just before the hump without having major fule consumption - whereas the semi-displacment hull in this case will apparantly get as far as 18 knots before using the same as the planing hull of mine.

So the comparision just does not hold.

Balance sheet:-
Belt along crusing all day at 25 knots using 0.6 mpg with noone able to make tea, get to the toilet without hurting themselves etc
OR
Go along at 18 knots, much more comfortably still getting 0.6mpg but with the ability for everyone to enjoy the passage and have the option of going slower and saving fuel or even displacment speed with one engine and using one third of the fuel. Add to this the option for long range crusing and almost double the living accomodation - the ability to dry out and so visit many more places that can be explored and that is where I am coming from.

My logic is fairly simple here, I just want someone to show me I am wrong ...

<hr width=100% size=1>Paul

 

[jfm]

Questions on your analysis gludy

Gludy 2 questions on that:

At say 10ish knots, is it really true a displ hull is more comfortable than a planing hull? If the whole hull is in the water I cant see why it matters much what shape it is, for a given lenght and beam. Is it just that disp or SD boats are 5 tons heavier?

If a planing hull and displ hull are the same length, why does the planing hull reach its hump speed sooner, not just a bit sooner but 13knots as opposed to 18. And if it does, isn't the planing hull better because if you push over the hump to 18kts you are then comparing 18 planing with 18 displ or semi displ, so surely the planing is more efficient on fuel?

Am i going worng somewhere?

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[longjohnsilver]

Am i going worng somewhere?

Think you just have jfm ;-))

Your logic all seems to make sense to me.

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[BrendanS]

Re: Am i going worng somewhere?

Something that's always intriuged me. Some hulls are incredibly efficient at high speed. Real high speed planing speed boats, stepped hulls etc most of hull out of water (using mine as an example, most fuel efficient at speed of 30knts), those same hulls use very little fuel at 4knts and even less at 2knts.

One of the reasons I'm happy to take long trips in a small boat with plenty of fuel onboard - either whip there at no time at 30 knts and beat weather windor, or slow way down, not 10 knts fuel guzzling, but just enough to maintain steerage and sit out the rough weather. Usually somewhere inbetween though.

Most boats can be used this way. At low speeds in rough weather, even my tiddler is quite stable as long as steerage way is on. Aren't big planing boats similar to displacement and semidisplacement hulls in this regard, other than big big displacement, and semi displacement often have stabilisers? It's speed that makes things uncomfortable underway, not necessarily hull design

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[jfm]

Re: Am i going worng somewhere?

"It's speed that makes things uncomfortable underway, not necessarily hull design" Yup, exactly.


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[Gludy]

Re: Questions on your analysis gludy

yes, I think you are making a mistake.

A planing hull will consume a lot of fuel just before it starts to plane - that is a very inefficient speed to travel at - get over the hump and start to plane and many have a very flat fuel consumption and so consume as much at 18 knots as they do at 25 knots. This varies but what you never do with a planing boat is stay at just before hump speed.

The keel and shape of the semi displacment hull are far more comfortable at 10 knots than a planing hull.

The semi-displacment hull will increase fuel consumption above hull speed yes but it can, say, have the same fuel consumption at 18 knots that my boat has at 25 knots, so in the higher speed the planing is more efficient, no doubt but it does not offer the flexibility or comfort of the semi-displacment hull.

I would sacrifice 7 knots of cruising speed in return for far more comfort., or if I want to sacrifice more, then I would also save fuel and add to comfort.
If I wanted to go a long way, I could treble my mpg.

<hr width=100% size=1>Paul

 

[Gludy]

Re: Am i going worng somewhere?

"It's speed that makes things uncomfortable underway, not necessarily hull design"

I just cannot agree.

Hull design is critical.

I went out in a Trader 575 at 24.5 knots in a 25 knot wind at Emworth harbour ... there was almost a 40 not wind hitting us underway - I could walk all around the boat, could have easily cooked a roast dinner.

In almost any seas when a planing boat is up and planing movement is very restricted. My boat at 25 knots in the same conditions simply could not have been as rock steady as that Trader.

The type of hull makes a huge difference. and more so at speed.

<hr width=100% size=1>Paul

 

[Gludy]

Re: Am i going worng somewhere?

Nope .. not exactly.

Are you telling me that a Nordhaven 50 footer with stabiliser on is no different when doing 9 knots in a f8 than a Princess 60 also doing 9 knots in a f8?

ifg you are then, wow planing boats should be crossing oceans..... absolute nonesense.

<hr width=100% size=1>Paul

 

[Gludy]

Re: Am i going worng somewhere?

But logic that states that the hull does not matter as regards comfort and the only criteria is speed that influences comfort is totally, totally wrong.

<hr width=100% size=1>Paul

 

[BrendanS]

Re: Am i going worng somewhere?

Wot happens if you put stablisers on the P60, just to even things up a bit? (OK, it won't plane well, but we're talking 9knts here)

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[Gludy]

Re: Am i going worng somewhere?

1. You cannot put stabilisers on a planing hull.#
2. weare talking about the point that speed effects comfort not hull design - so the argument goes that both hulls are the same comfort at 10 knots or 25 knots as regards comfort. ,,, that is not true - hull design matters.



<hr width=100% size=1>Paul

 

[BrendanS]

Re: Am i going worng somewhere?

so take the stabilisers off the N50. You can't compare one boat with stabilisers against one without, then argue the hull form is the only factor for comfort

This is a theoretical arguement anyway in many regards, so quite reasonable to take P60 with stabilisers as a comparison, no reason technically why it couldn't have them fitted, in a hypotheticalish sort of way.

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[Gludy]

Re: Am i going worng somewhere?

"then argue the hull form is the only factor for comfort"
in no post have i ever argued that. I argue that speed alone is not the only factor - its hull form as well - this was to counter the argument that hull form does not matter.

"no reason technically why it couldn't have them fitted, in a hypotheticalish sort of way"

Please let me explain .... I started the thread on on imaginary boats or hypothetical boats but discussing real world choices between boats.

"This is a theoretical arguement anyway in many regards"

Nope its a real discussion about real world choices.

There is every reason why in practice you cannot fit stablisers to a planing hull - they would prevent it planing for a start!

" so quite reasonable to take P60 with stabilisers as a comparison"

Ok lets do that ... it would never plane as the ride would be all over the place.

Why is that duscussions like this have to end up at extremes rather than have folks simply face the truth that is staring them in the face ... hull form is a significant factor in crew comfort. speed is another, sea state another but as far as the boat is concerned its the hull shape and speed that matter.





<hr width=100% size=1>Paul

 

[Newbroom]

Re: Am i going worng somewhere?

No boat travelling at below its displacement speed will use a lot of fuel. Its once the boat approaches its displacement hull speed that the design of hull will alter it sea keeping, comfort, and economy.
Comparing semi displacement hulls like a Trader with Fast planing boats is like comparing Volvos with a Ferrari, pointless. At different speed they have the same economy they will both do the same job but they are designed to do it in different ways.

The semi displacement hull was untill recent years a bit of a comprimise between displacement and planing but with modern engines and hull designs allowing planing hulls to plane a much lower speeds and with none of the getting over the hump which was once a major hurdle, it could be said that there is no need for a semi displacement design at alll.

That is only half the story, With most semi displacement boats you get

More space foot for foot
A stronger heavy lay up
Ability and designed to travel at any speeds from 0 to max
Ability to travel longer distances weight of fuel is not an issue.

Are they any more economical no I dont think so, unless you are prepared to slow down.

During delivery work taking boats across the bay to the Med I find that by the time I make Gib there is little to choose in fuel consumption . But that is because I am not using the planing hull like it is designed to be used which is on the plane.

What do I prefer, semi displacement , because of the range and I know that if I got into a heay sea situation with just my wife as crew we can slow down to below displacement speed and still make progress even on one engine. Would I feel a safe in a planing hull in the same situation in a planing hull 150 miles plus from land the answer has to be no. Also price is a major factor.

But if I was a looking for a fast boat for journies of 200 mile and less and as a holiday recreational boat I would buy P60 Squadron etc.
Its horses for courses and we usually buy what appeals to us and what we are going to use it for.


Dave




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[Gludy]

Re: Am i going worng somewhere?

I agree with what you said but there are a few points:-

"planing hulls to plane a much lower speeds and with none of the getting over the hump which was once a major hurdle,"

Are you saying that fuel consumption just before the boat lifts and starts to plane is not higher than when its on the plane?

"it could be said that there is no need for a semi displacement design at all."

It could be said but then so could anything that is not true be said without making it true. Later in your message you explain in detail most of the reasons why it is not true.

"But if I was a looking for a fast boat for journies of 200 mile and less and as a holiday recreational boat I would buy P60 Squadron etc."

If I was med based for journeys like that out of a marina so would I. However you state that "the design of hull will alter it sea keeping, comfort, and economy" therefore we agree.

Do you agree that it would be absurd to fit stabilisers to a P60?

Cheers






<hr width=100% size=1>Paul

 

[Deleted User YDKXO]

Re: Am i going worng somewhere?

Unfortunately the Nordhavn hull is very different from the Trader hull, it has been specifically designed for displacement cruising whereas the Trader's hull has been designed for semi displacement speeds. In fact, the Trader hull is much closer to the Sq59 hull in design that the Nordhavn, the only major difference being the keel which may add a certain amount of directional stability at low speed. Btw you cannot assume that this keel would allow the boat to dry out. The keel may not be designed to take the weight of the boat and the props may still protrude below the keel - you would need to check this with Trader. Obviously you would need legs as well to ensure the boat dried upright

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