Surface Piercing Drives - Better than Outdrives?

[roykinch]

Hello

Can someone please tell me with something I have always wanted to know?

I have a Sunseeker Portofino 375 and would like to go a bit quicker, so i have been looking at Sunseeker Superhawks.

The 48 mostly has 3 engines (3 x the trouble), the 34's & 40' (40' being the same as 34' with 6' swimdeck).

I do keep noticing very fast 34'/40' when having Surface piercing drives hitting up to 50 knots.

My question is - if you get better performance from surface piercing 3 blade props and have no outdrives to service etc, Why don't all boats have them?

 

[mateyboy]

It's been done quite a few times already and in short the surface drives are quicker at higher speeds but poor at low speed handling, cost similar to drives to services and are more fuel efficient at higher speeds than shafts or drives. I can't weigh up why they're not more popular in UK, there's loads on the med.

 

[Nick_H]

Surface drives are only more efficient than outdrives at very high speeds, and you usually can't travel at those speeds in the UK due to sea conditions. Most cruisers aren't bothered about such high speed anyway, as it comes with a very bumby ride. SD's are also more expensive to install in the first place, don't reverse too well, and not everyone likes the rooster tail.

How fast do you want to go? My 34' boat does 45 knots on outdrives, with quite small engines.

 

[mateyboy]

Surface drives are only more efficient than outdrives at very high speeds, and you usually can't travel at those speeds in the UK due to sea conditions. Most cruisers aren't bothered about such high speed anyway, as it comes with a very bumby ride. SD's are also more expensive to install in the first place, don't reverse too well, and not everyone likes the rooster tail.

How fast do you want to go? My 34' boat does 45 knots on outdrives, with quite small engines.

In all honesty I coming to the conclusion that 25-30kts is more than ample, and plenty of room on board would be ideal also.
What boat/engines is your 34'er Nick?