Thanks Dave.

HI John
You will get roughly the same sort of performance with NiMh at a lot less cost and with a lot less hassle over the batteries. The Tamar is a fast afloat boat but will not need the same continuous performance as say a fast racing boat. I use NiMhs in my Trent lifeboat and get all the speed I need and if I run out of power I just put in a second set of batteries.
Cheers
dave

Brilliant!
Many thanks Dave.
P.S do you think nimh batteries would be more suitable?
Thanks again.
John.

HI John
The motors will be OK on 14.4v see below:

Motor Nominal Voltage Voltage Range No-Load RPM NO-Load Current Current @ Max Effic. Stalled Current Max Efficiency Case Length Case Diam Free Shaft Length Shaft Diam Weight
Speed 700 TURBO 9.6v 4.8-14.4v 15,000 2A 12.5A 65A 75% 67mm 42.2mm 14mm 5mm 320g
Speed 700 BB TURBO 9.6v 4.8-16.8v 13,000 2A 15A 77A 75% 67mm 42.2mm 14mm 5mm 350g
Speed 700 RACE 9.6v 7.2-9.6v 19 000 3.3A 17.5A 90A 69% 66mm 44.5mm 10.5mm 5mm 362g
Speed 700 BB TURBO 12v 7.2-19.2v 11,600 2A 12.5A 43A 75% 67mm 44mm 14mm 5mm 350g

As you can see there are quite wide variations in the spscs and apart from the race version all will be OK.
They are fairly heavy current so you will need some beefy ESC's, probably at least 100 amp but preferably 150 amp. As you are using LiPo you will need ESCs that will cut the power to the motor when the safe discharge voltage is reached. I have a timer on my Tx that warns me before the power is reduced.
There are many suppliers of ESC on the web and in the UK. I would be wary of some of the Chinese suppliers as they can and do overrate the capacity on their ESCs. if the wiring is not substantial then it is unlikely the current will be as indicated.
Good hunting
Dave

Thanks Dave.Am building Speedline Taymar powered by 2 Graupner 700 bb motors,not decided on ESC.
John.

HI John
Welcome to the site. The motor will run a bit fast and may overheat at this higher voltage. The main constraint will be on the Esc you are using. There will be a max voltage capability for this component and using a higher voltage will cause damage. if you can post a bit more info about your setup it will be possible for us to give you more specific advice.
Cheers
Dave