How realistic is it to use a Planing boat at Displacement speed?

[stillwaters]

We are thinking of relocating our boating to the Adriatic and will want to spend at least 80% of the time enjoying the journey at 8-10knots. Trouble is, there seem so few semi-d boats around, and the few there are tend to be let down by various drawbacks, not the least being unspectacular interiors that have done nothing to convince the wife that splashing the cash on another boat will be far more fun than wasting it on some villa somewhere. However, she does seem to warm to some of the more apartment-like accommodations that we have seen on some planing boats, Fairline, Azimut & Prestige, for example.
So, could anybody already familiar with the area please pass on their wisdom about the viability of using a 50-60 foot planing boat also fitted with some form of stabilisation, probably a Seakeeper. Its use would also be made a little more critical by our current pattern of use, which consists of 10-12 day jaunts away from base, and therefore necessitates being able to return on time to catch flights home.
Thanks in advance for all the gems that are now sure to flood in.....................hopefully.

 

[BartW]

last summer we navigated our planing boat all up the croatian coast from Porto Montenegro to Istria Rovinj and crossed the adriatic to Venice,
and back,
almost alway's at 10kn, in our planing 70ft boat (boat has retrofit zero speed fin stabs)
the only part we did at 20kn was half of the adriatic crossing in order to arrive before dark in porto Elena in Venice !

for the way up to Venice we had one week (and still time left for swimming and relaxing every day!)
we stayed one week in Venice,
and route back we had 4 weeks for exploring the croatian coast
(several change of guests inbetween)

there is no reason why this would not work.
our boat size is perfect for sailing at 10kn, (= just slightly above our D-speed)
but has no problem doing 20kn (tax free fuel in Porto Montengro helps )

previous years we used to sail 50% at P en D speed each,
first year of ownership was 100% P speed
we own the boat 6 years, and there still is any desire to change boat, and certainly not to D or SD
If I had to buy again, it would be a 70ft Planing San Lorenzo

imo if you sail a lot at D speed,
and your P speed is not much faster than 20kn,
I would not choose a gyro, but stab fins

you and your wife are welcome to visit us on Blue Angel, and experience the feeling.

 

[stillwaters]

last summer we navigated our planing boat all up the croatian coast from Porto Montenegro to Istria Rovinj and crossed the adriatic to Venice,
and back,
almost alway's at 10kn, in our planing 70ft boat (boat has retrofit zero speed fin stabs)
the only part we did at 20kn was half of the adriatic crossing in order to arrive before dark in porto Elena in Venice !

for the way up to Venice we had one week (and still time left for swimming and relaxing every day!)
we stayed one week in Venice,
and route back we had 4 weeks for exploring the croatian coast
(several change of guests inbetween)

there is no reason why this would not work.
our boat size is perfect for sailing at 10kn, (= just slightly above our D-speed)
but has no problem doing 20kn (tax free fuel in Porto Montengro helps )

previous years we used to sail 50% at P en D speed each,
first year of ownership was 100% P speed
we own the boat 6 years, and there still is any desire to change boat, and certainly not to D or SD
If I had to buy again, it would be a 70ft Planing San Lorenzo

imo if you sail a lot at D speed,
and your P speed is not much faster than 20kn,
I would not choose a gyro, but stab fins

you and your wife are welcome to visit us on Blue Angel, and experience the feeling.

Thanks for all the info, and especially your invitation to visit you on BA. We walked past BA in November en route to seeing Mad Pad's boat parked near yours, she certainly looks big enough to handle most conditions. PM also looks an interesting place to visit, especially with the tax-free fuel you mentioned, and we had already found how delightful Kotor and the surrounding region is on a previous visit (on a 65,000 tonner, mind you).
In view of your own experience in those waters, I guess that at least most of the time a reasonable sized planing boat will handle the conditions. My real concern, though, is if we were to be confronted with having to cover the final 50 or so miles of a trip back in far from ideal conditions, would the planing boat cope, and maybe more importantly, would the crew, or would a sharper entry semi-d be a more sensible option?

 

[Whitelighter]

We use our 50ft Ferretti almost exclusively at displacement speed and have no issues.
We havent really tested her in the rough (an I dont really intend to) but dont have too many concerns

 

[BartW]

......In view of your own experience in those waters, I guess that at least most of the time a reasonable sized planing boat will handle the conditions. My real concern, though, is if we were to be confronted with having to cover the final 50 or so miles of a trip back in far from ideal conditions, would the planing boat cope, and maybe more importantly, would the crew, or would a sharper entry semi-d be a more sensible option?

imo there is little to no difference in the ability to handle bad condition, between a P or a average D/SD boat in that size range,
as long they are stabilized, and in this case, fin stabs! (gyro is less efficient during navigation)

moreover with a P boat you have more headroom of power to play with when handling a big swell.

imo on a heavy sea, a pleasure boat either D, SD or P, is just a floating tub !
the main thing to do is taking the waves at the correct speed and correct angle.
we have had situations with green water over the bow, and we needed to alter throttle when mounting or decenting the wave,
I don't believe that a pleasure D or SD mobo would have been different

afaik the only exception to this are the long range blue water cruisers such as nordhavens, or coastguard boats.
which are totally closed for water, and have a self righthning construction.

stabs is what you need when you want to avoid people getting seasick during navigation in heavy sea.

 

[Nigelpickin]

Agree with all that's being said, our prestige 500 spent most of last season at 8 Kts on our 1600 mile trip. Very pleasant and economical.

Head and following seas are fine, long swell from the side is also fine; it's just anything from the quarters that gets uncomfortable.

If you have the time to pick your days and travel with the wind on your side then I'd recommend it wholeheartedly.

As has been said, having the power on tap to motor on through if you find things are unpleasant is a real boon, just don't take too long making your decision to speed away; you can always slow down later if the conditions improve. You will definitely need to stow your boat well!

 

[mainshiptom]

I always travelled at 10 Knots on my Mustang M43, I was lucky enough to have fuel consumption monitors on the lovely white lumps.

Full speed 35 Knots would have taken 200 litres per lump but at 10 knots we kept each engine at under 10 liters.

that meant that a trip say Like St Kats 5 hours would be around £100 for the whole family,

Never had any issues with engines or boat , we also travelled down to Eastbourne at quite choppy seas and again slow but comfortable,

 

[paul salliss]

We use our 50ft Ferretti almost exclusively at displacement speed and have no issues.
We havent really tested her in the rough (an I dont really intend to) but dont have too many concerns

Am curious to know why do you you drive her almost exclusively at displacement speed, is it just a cost of fuel thing?

 

[Whitelighter]

Am curious to know why do you you drive her almost exclusively at displacement speed, is it just a cost of fuel thing?

Cost/fuel use is a factor, but at 9knts with the ap on I don't have to hang onto the helm, the beer stays upright and it's easy to have a nice relaxing chat. The kids can sit on the front and since we are on holiday it doesn't matter if it takes an hour or three hours to get there

 

[Portofino]

We do it D speed more and more nowadays .
Combo of fuel € ,and as Jez says there's no rush .Just like spending time taking in scenery and boat / people watching .
Typically we go off after a lazy am start 10-20 miles @ 9 knots consumption is 38 L/H total .
Anchor -sunbath ,swim ,go ashore ,paddle board etc ,then return .
If the 1st bay for what ever reason we dicide to move ,I may blast 30 knots for 10-15 mins to somewhere else .
Sometimes it's so hot we plan a long 6 hr or so D speeder to keep a nice breeze while folks sleep on the sun pad .
I can sit Helming all day too getting a tan .
Another reason is safety .it can get crowded and busy in high summer in the Cote dAzur ,
At P speed frankly I,am have to work too hard on the helm and there are the pots !
D speed hopefully avoids this ( not me ---this time )

Back to the Op ,sQ yup you can cope long passages in a P boat. @ D speed , and have the ability to outrun weather .
Last Y we were spending some time @ Porqueroles islands /area -idea was to bum around for a week or so .
However a Mistral was due after 4 days .
We found a safe headland and tucked in @ anchor etc . But at 6 pm while cooking dinner ,wife wanted to go back ,--like "do we have to sit here for next 2-3 days ?" --- good Q I thought .So @ 6-30 dinner over and 70 miles from our home marina we up anchored and I bombed back down wind riding 3-4 M waves and increasing - or more ? - @30-32 knots
By 8-30 pm just before dusk - July - we were tied up ,shore power on A/C on in our marina -having on spec covered 70 miles ,cost 400 + L -but everybody happy .

So if it's the ride -comfort side of things that seemingly figure high in your next boat choice -basically IMHO it's rhe hull shape you need to investigate Deeper V ,s are smoother than less shallower V,s --- makes a huge difference to the enjoyment of the boat .
Funnily enough we have not noticed any roll to the extent it spoils the ride or we need to think about stabs .
Not deriding stabs ,but some boats ,hulls will benefit more from stabs than others .Ours just cuts through more rather than lift up and induce roll.
I can and do adjust the speed to gain a flat smooth ride in a chop ,upwind 1/4 beam or what ever ,

I wonder if somtimes stabs are riding a wave (excuse the pun ) of popularity these days because of this modern trend of rolly boat hull design -you know -engines pushed back aft ,to accommodate a mid cabin , flat aft sections to gain lift ,due to -engines Hp on the edge ,fuller bow sections ,-more appartments ,than sea craft ?

I think that's the direction of travel in hull design -accomodation not seakeeping --opens the back door for stabs .

 

[vas]

Cost/fuel use is a factor, but at 9knts with the ap on I don't have to hang onto the helm, the beer stays upright and it's easy to have a nice relaxing chat. The kids can sit on the front and since we are on holiday it doesn't matter if it takes an hour or three hours to get there

+1000
I notice that down here most old seasoned moboers feel the need to actually helm, and believe me you really don't want to helm 60nm legs at 8kn under the sun, hence they go everywhere at 18kn. As a result they don't visit many places as fuel is becoming a serious parameter.
Once they are introduced again to A/P and start turning on their chartplotters, you could possibly persuade them that 8kn is fine if you're isle hoping (15-20nm per day) anchoring in different bays for the morning and afternoon swim. My three friends with 39-45ft princesses here still give me strange looks when I'm telling them about how great an a/p is I've yet to persuade the two to turn it on and check the manuals to remember how to use it . Needless to say we are talking about 20+yo electronics here...

cheers

V.

PS out of the 600+nm done with MiToS there are around 20 at planning speed and half of that were due to some F6 wind whilst following a sailing yacht race with the two leaders doing more than 10kn and I had to catch up and get the finish line buoys ready before they reached the finish line

 

[stillwaters]

as long they are stabilized, and in this case, fin stabs! (gyro is less efficient during navigation)

Yes, given the choice of either, I'd rather have fin stabs. Unfortunately though, finding used boats (too impatient to wait for a shiny new one, and besides, prefer for others to take the initial depreciation hit) with fins seems nigh on impossible, whilst there are at least a few around now with Seakeepers.

If you have the time to pick your days and travel with the wind on your side then I'd recommend it wholeheartedly.

That's why I asked in the first place. Because of our intended use, we won't always be able to sit out poor weather and will just have to go for it. Obviously, in the case of really extreme conditions, it would be a no go anyway, but in anything less it would be good to be able to go out with a hull that gave a reasonably comfortable ride without slamming, which I've encountered before when on somewhat smaller planing boats.
Btw, I've noticed a few 550s with gyros fitted under the gennies, which I think in turn are mounted high on a frame as standard. Is this also the norm for the 500, and do you know if it would be possible to install a Seakeeper 5 in a similar fashion?

Cost/fuel use is a factor, but at 9knts with the ap on I don't have to hang onto the helm, the beer stays upright and it's easy to have a nice relaxing chat. The kids can sit on the front and since we are on holiday it doesn't matter if it takes an hour or three hours to get there

That about sums up our own ideal boating. Strangely though, I constantly get criticised for driving cars too fast - oh well! :nonchalance:

I wonder if somtimes stabs are riding a wave (excuse the pun ) of popularity these days because of this modern trend of rolly boat hull design -you know -engines pushed back aft ,to accommodate a mid cabin , flat aft sections to gain lift ,due to -engines Hp on the edge ,fuller bow sections ,-more appartments ,than sea craft ?
I think that's the direction of travel in hull design -accomodation not seakeeping --opens the back door for stabs .

As we know though, the womenfolk usually buy the boats, and because we need to keep them onside, we go along with it - and we can't blame them for putting the accommodation before the techie bits, can we???
It reminds me of a guy I met about a dozen years ago, desperate to trade his existing boat for something a little more interesting and with a million to spend. Unfortunately though, his wife wanted a villa. As he said, a villa would be fine for the first 2 weeks, but then what would he find to do? So he trawled his wife round all the blingiest million pound boats he could find at the time, such as SunPrinFair etc., none of which she liked. However, the one she did like was the Sealine 60 that had just come out, which would never have been his own choice and the only one out of all of them which would have resulted in him writing-off about half of its cost almost as soon as he'd bought it. However, if it was that or the villa..........

Thanks to all for the helpful advice.

 

[TonyR123]

Btw, I've noticed a few 550s with gyros fitted under the gennies, which I think in turn are mounted high on a frame as standard. Is this also the norm for the 500, and do you know if it would be possible to install a Seakeeper 5 in a similar fashion?

That is exactly where it is fitted. Having a Seakeeper 5 fitted my 500 currently being built. Not a factory fit option but has been fitted on other 500s that way. Still fits fine even with the tender garage.

 

[stillwaters]

That is exactly where it is fitted. Having a Seakeeper 5 fitted my 500 currently being built. Not a factory fit option but has been fitted on other 500s that way. Still fits fine even with the tender garage.

Useful to know, thanks for that.

 

[QBhoy]

Hate to be a bore, but you'll no doubt be aware that it wouldn't be great for the engines subjecting them to low speeds for sustained periods. Likely to cause glazing and carbon build up. As long as you give them a good blast every now and then, should be ok.
Big turbo charged diesels are designed to be worked hard from time to time. If the turbo isn't spinning up, combustion dynamics won't be great and likely to carbon up. If the engine(s) doesn't or don't get worked a little, they won't get up to designed operating P's&T's.
If you solely plan to go at displacement speeds and have no interest in planing for a sustained period, a way round this might be to lower the pitch of the props. This will allow the engines to work a little harder, but fuel consumption will no doubt increase.
A bit of a dilemma....higher fuel cost or risking damage to expensive lumps.
Sorry to be a spoil sport....just a thought.

 

[Portofino]

Likely to cause glazing and carbon build up. As long as you give them a good blast every now and then, should be ok.

Big turbo charged diesels are designed to be worked hard from time to time. If the turbo isn't spinning up, combustion dynamics won't be great and likely to carbon up. If the engine(s) doesn't or don't get worked a little, they won't get up to designed operating P's&T's.
------,
Sorry to be a spoil sport....just a thought.

Nope , good points
We do give ours an "Italan tune up " usually @ the end of a D speed run. .
How ever with % load gauges and Exhaust Temp Guages in view of correct "T + P ,s " I run D speed slightly a few rpm,s higher than real top D ,to load em up
9 knots (WL lengh 42 ft ) reads load 50% ish .@900 prm and EGT ,s below 400 oC

Optimim combo is just around 1750 rpm -sweet spot - load is 75 % -, EGT 535 oC and consuption 85 L/h each .
Speed is 27 knots -this my Eco cruise .

Certainly you are right -the forces involved in compression ignition -diesels are in a different leugue to petrols and many folks don,t realise that they actually need high rpm ,or put this way were designed for optimal running re wear -what I mean REDUCED wear and long life @ optimal rpm - all the relative expansions and sealing of the moving parts is calculated for correct Temp and pressures .
Lower than these for sustained periods or higher ( excessive EGT --- every marine diesel should have EGT measurement !!)
Will reduce the life .How ever having said that it's a complex subject there are other variable s like
Fuel quality re carbon build up /acid pitting -sulphur
Oil quality --- most important follow manufacturers. Reccomendations --- many do not --urghhh !

There's a bit here about the bores and rings ---they need the correct T + P's to work best
http://home.ufam.edu.br/berti/nanomateriais/8403_PDF_CH33a.pdf

 

[paul salliss]

So in this thread a number of people have decent sized boats and are driving around at D speed, for reasons I understand, and fuel has a lot to do with this thread if you read the whole thing, so, if any of you had your time again would you have bought a real D boat, Dutch steel type of thing or Nordhaven type of thing. I find the biggest issue with the forum is people getting pissy always defending the decisions they have made but if you were being objective, and could turn back the clock knowing what the cost of fuel would ramp up to, what boat would you have now?

 

[Portofino]

So in this thread a number of people have decent sized boats and are driving around at D speed, for reasons I understand, and fuel has a lot to do with this thread if you read the whole thing, so, if any of you had your time again would you have bought a real D boat, Dutch steel type of thing or Nordhaven type of thing. I find the biggest issue with the forum is people getting pissy always defending the decisions they have made but if you were being objective, and could turn back the clock knowing what the cost of fuel would ramp up to, what boat would you have now?

The same an Itama -cos of the ride 1st and it's pretty good if you use it as a Med boat .-Gloryfied swimming platform and toy for dad keeps him occupied .

I just have a mental man maths ball park annual fuel spend ,so it's speed Vs time on the engines = range .
The fuel thing has not really figured in to how we use the boat and it's one of many facets of the total cost of ownership .

A simple "man maths " equation that works for me is to x ref the fuel bill with a Cote d Azur hotel bill (s)
Fuel is Allways less in my mind for a given stay .

I would not say folks are justifying there boat choice ,just thinking aloud -- in a forum esq way ? but back to the Op,s thread
With a P you can D ( within the realms of good engine housekeeping ) but you have the option of beating the weather -bugging out or making that flight etc .

 

[paul salliss]

The same an Itama -cos of the ride 1st and it's pretty good if you use it as a Med boat .-Gloryfied swimming platform and toy for dad keeps him occupied .

I just have a mental man maths ball park annual fuel spend ,so it's speed Vs time on the engines = range .
The fuel thing has not really figured in to how we use the boat and it's one of many facets of the total cost of ownership .

A simple "man maths " equation that works for me is to x ref the fuel bill with a Cote d Azur hotel bill (s)
Fuel is Allways less in my mind for a given stay .

I would not say folks are justifying there boat choice ,just thinking aloud -- in a forum esq way ? but back to the Op,s thread
With a P you can D ( within the realms of good engine housekeeping ) but you have the option of beating the weather -bugging out or making that flight etc .

I agree with most of that, and like you fuel to me is just part of the deal, I don't think about much really

 

[Sojourn]

Hi I've done quite a few delivery trips on my boat and clients boats and a lot of the time at displacement speeds. Like all planning boats they are primarily designed to get over the hump and plane, but if the conditions are right, dis speed is great, comfortable, fuel efficiency and you enjoy the time at sea. I delivered a new princess 82, lovely boat, most was done at dis speed with the occasional burst to spin up the turbos.