T-Pain Is On A Boat: Re: [Electric Boats] Tartan 27 conversion

Tuesday, September 28, 2010

Re: [Electric Boats] Tartan 27 conversion

Paul,

You will need to support the inboard end of your prop shaft with a thrust bearing. A two or four bolt ball bearing flange from a bearing distributor is the way to go. MRC brand flanges have a plastic housing and rust resistant plating on the steel components. The size that fits your shaft will have plenty of capacity to handle the shaft and belt loads.

The bearing distributor will sell the pulleys and belts too. Use a toothed rubber belt.

The Gated web site has an excellent pulley and belt selection program.

With the $1400 kit you might spend another $500 to $750 on parts, and several hundred more if you need to pay a machine shop for fabrication. The mounting system has to be rigid and accurately align the motor with the prop shaft. You will also be happier if you connect it to the boat with rubber vibration absorbing mounts.

The "drop in" systems will save you many hours and probably fit right on your old A4 mounts. Also, the throttle box and wire harness in the $1400 kits is golf cart rated - not marine stuff. Like many things, you can trade $$$ for time and specific skill.

Denny

PS: I see you are in Annapolis. You should go to the start of the Wye Island Marathon (if there is one this year) in St Michaels and check out the electric installations. I think it's this Friday 10/1.

----- Original Message -----

From: tartan27hull157

To: electricboats@yahoogroups.com

Sent: Monday, September 27, 2010 11:55 PM

Subject: [Electric Boats] Tartan 27 conversion

Hi all,

I have been lurking and reading for some time while I nurse the 45-year-old Atomic 4 in my Tartan 27, a 27 ft LOA, 21 ft LWL, 10,500# displacement-hull sailboat (currently propped with a 13x8x2).

It seems like a reasonable replacement for this boat could be built around a 4kW motor with a 2:1 reduction and as much battery as I can afford from a weight and $$ perspective (it would save some money if the initial installation could preserve the current prop and shaft, and if my calculations are correct, that prop should push the boat to hull speed around 1700 shaft rpm...sound right?)

I am puzzled by the price difference between $1400 kits which seem to be lacking only the reduction system and the batteries (eg EVParts, ThunderStruck), and $4000 systems which purport to be "drop in" except for batteries (eg SeaNav, ElectricYacht).

Am I missing something? It seems like with the extra $2600 and a McMaster-Carr catalog I should be able to buy some pulleys and belts and bearings and angle iron, build the DIY system, and still have some pocket change left over to buy batteries. Am I overlooking a significant component?

Also, my prop shaft as designed is supported only by the cutless bearing and the big, heavy engine's output flange. Should I plan on stabilizing my prop shaft somewhere in the shaft alley with a strut, or can the smaller electric motor be installed in a robust enough way that it supports the shaft?

Thanks in advance, Paul
Tartan 27 #157
Annapolis, MD