Fairline Targa 34 - advice please.

Cd: I did say 33k fully loaded with some to spare and believe me, you would not have been able to sustain 22/24k in the conditions I experienced last week! So rough in fact my new Spinlock life jacket activated whilst I was at the helm! Cant think why, it was not submerged! Must have pulled the cord? Anyway, dont want to hijack this thread. 38K at 3000 seems excellent you are obviously better than I am trimming the boat and outdrives, I'm still learning........
 
dont jump on John
in the med in Summer a boat can loose easily 25% of its top speed versus what it does in UK,
so a loaded top speed of 38 knots with KAD300s should be good
10 knots seems slow in a force 5 head, but may be it was your inexperience in such a sea
still better slow then flying so if it felt good you did the right thing
in the med it can be very tricky and also depends sometimes wind direction as this creates a total different wave pattern
was in a similar situation with T37 NE once and altough I was peaking 18 knots it was very uncomfortable and bumpy, I think that my 27 Sport can sustain better slow planning speeds then the Fairline T37 which comes usable in these sort of seas
for 120k I would also look for a Prestige 34 S HT, there was a post about a discounted one a few weeks ago here
 
Thanks Poweryacht - yes I am inexperienced and need/welcome the advice of fellow MOBOs. I am Day Skipper Practical with Yachtmaster Theory - I now have around 1,000 NM under my belt at present. I want say another 1,000 NM before I take my Coastal/YM Practical, so welcome all advice and if appropriate constructive criticism! I trimmed the boat as trained and taught by Jon Mendez who accompanied me in April from Brighton to Torquay, we experienced similar conditions passing the Needles and through St Albans Ledge.

In the Med the waves at one point were coming fast and furious off our STBD bow and often sprayed over into the cockpit. It seemed a very heavy sea to me, with frequent white crests and breaking waves with some foaming. Having checked the forecast carefully before I left, which seemed correct for the first 20 NM (Flat F1/2) it was challenging but I was confident and after the event found it very enjoyable, I am sure you will understand what I mean! My log read 16k but actual SOG was around 11/12k? When I tried to accellerate above this speed, the frequency of the waves just seemed to pick us up and slam us very hard even with bow trimmed down. It felt safer to throttle back in these conditions and steer my way through the waves. Obviously every situation is different so any advice would be welcome/appreciated! Sorry to Nicololo for hijacking part of your post!
 
John I like it!!!

1000NM under your belt and Yacht master theory!!! You havent got a clue about boats have you!!!??? /forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif

LMBO!
jas.
 
[ QUOTE ]
in the med in Summer a boat can loose easily 25% of its top speed versus what it does in UK

[/ QUOTE ]

25% of its top speed means anything up to 50% of its power, have you really found anything like this? I have only ever heard of one or two knots difference due to the med heat. Are you also including more fouling of the hull, which I agree could have this kind of effect, but a fouled hull would slow a boat in the UK as well?
 
[ QUOTE ]
[ QUOTE ]
in the med in Summer a boat can loose easily 25% of its top speed versus what it does in UK

[/ QUOTE ]

25% of its top speed means anything up to 50% of its power, have you really found anything like this? I have only ever heard of one or two knots difference due to the med heat. Are you also including more fouling of the hull, which I agree could have this kind of effect, but a fouled hull would slow a boat in the UK as well?

[/ QUOTE ]

yeah 25% was the limit number but sometimes with sterndrives in does happen
with shafts it is a bit less I agree
I included also the HP you loose from the engine cause of the heat
surveyors tell me Volvo engines are more prone to this as they test there engines in cold temperatures, and esaily loose 10% of there rated HP add the 10% you loose cause of the hot water and there you go
water penetration in the hull is also usually more in the med versus the UK
 
well you clearly know your boats, so i'll bow to your greater knowledge that some boats show such a different performance, although intuitively I can't see it could have such an effect. Even a 10% reduction in hp would only effect the top speed of most planing mobos by a couple of knots.

I understand why air temperature reduces hp, and therefore speed, what effect does warmer water have?
 
Cant get all techy (cus I aint anyway) but from my experience over several seasons of med and UK boating, the difference in top speed between identical boats can be as much as 3-4 knts , brand new factory fresh the ABS 47 will do max 39 knts in the med but 43 knts in the Solent. Fouling this year in La Nap seems to have been worse so by the end of the season our 45 with twin 350 D6's and high humidity would only pull 31 knts and that was a struggle. In the UK the same boat last month even with some fouling did an easy 34knts and steam cleaned off got 37 knts. Humidity seems to have a big affect and the warmer water I expect doesn't have the same cooling affect so perhaps there is a few degrees diff in engine temp or ceratinly the cooling of the fuel, cooler fuel seems to burn harder.
 
[ QUOTE ]
cooler fuel seems to burn harder.

[/ QUOTE ]

Apologies for the thread drift. What you say is interesting.

In summer I get better mpg out of the car, than in winter. Surely it should be the other way round? Surely colder denser air has more oxygen in it per cc, so therefore the bang should be bigger. Also the intercooler will be doing its job better. Along with colder fuel burning harder, if indeed that is the case.

Also, I appreciate that the air being moved by the car in winter will be denser, but the equation would be directly proportional to that in summer, so mpg would be the same all year round........shouldn't it?

Should also apply to the boat. Colder air & colder water (& fuel) in winter, should make the boat faster & less thirsty. Right?

Somehow, I don't think so. Anyone able to clarify?
 
Colder denser air has more molecules of oxygen for any specific volume than warmer air. More oxygen will allow the engine to burn more fuel thus providing more power from each revolution.

It is correct that you will there for need less throttle to produce the same speed in winter and therefor the car should be more efficient. Of course, if you dont recognise this and dont modulate your driving (ie you use the same amount of throttle regardless) you will be accelerating more quickly and probably using a bit more fuel.
 
[ QUOTE ]
It is correct that you will there for need less throttle to produce the same speed in winter and therefore the car should be more efficient.

[/ QUOTE ]

Can't see that. Assuming the engine burns cleanly either way, which it should do with a modern electronic control, then in winter it will have more power at the top end, but will burn more fuel. So to achieve the same cruising speed, you will need a bit less throttle in winter, but the same amount of fuel and oxygen will be used, hence the same fuel efficiency?
 
I agree, but most of my driving tends to be long distance / motorway stuff, usually on cruise. MPG is definitely better in the summer.

Maybe having lights on, heaters on etc in winter saps a bit, but then so does the aircon in the summer. Still baffled.
 
Turbos work hugely better in rally cars in cold, damp air, thats why our old Evo 8 used to have water injection into the intercooler............must follow suit that boat engines would need the same in hot climes??
jas.
 
I think 2-3 knots less in n the Med on my S34 with KAD32's is about right against the figures Sealine quote. Fouling of the outdrives can have a dramatic effect, and has been particuarly bad this year - I lost 10 knots in 4 weeks! but soon found them again with a snorkel and scraper.
 
We've had our 2004 T34 for just coming up to 3 years now and still adore it. She's fitted with the KAD300's, so getting the valve clearances done every year is a bit of extra expense, but tocuhwood we have never had a serious problem, apart from one, where some clot of an engineer duffed things up putting rocker cover back on without a gasket and filled the bilge with oil... She absolutely flies, cracking about 41 knots with 25% fuel and 25% water, but loaded with half a brewery and vineyard. Handling wise, just can't fault it for a boat this size. We came back from Burnham on Crouch once with a couple of other boats, 1 a Prestige 34, the other a Falcon 34, one of those pretend fly bridgy things, and couldn't believe how much spray was being thrown onto the P34 in only a F3-4, we were bone dry, mind you the poor Falcon fared even worse... Ours has done about 750 hours now, so gets plenty of use, so good luck with your boat choice and enjoy whatever you end up with, just make sure you use it when you do get it!
 
OK - in summer we encounter warmer air which is less dense so marginally reduces combustion efficiency. The air however is easier to move out of the boats way and if the water is warmer too so is it - all negligible?

Surely more likely the effect is with the performance/ability of the prop(s) to move a more saline and less dense warmer water due to its higher temp? For instance an 8C difference in temp will itself result in a 3% drop in output. P1/P2=(273+t2)/(273+t1) therefore with warmer water at lower density less mass will be propelled which is after all the motive force and hence a drop in boat speed? As clear as mud to me........
 
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