[PCW] Motorsailer cat

Sun Dec 30 17:49:46 EST 2007

The cat has a sailing hull form that has evolved over several iterations designed and built by Tim Mumby in Australia, and further tweaked by at lest 2 NAs. LWL is 49' and hull L/B is 12.5/1. 

My boat had the 4mm plating computer cut in Oz then shipped to Thailand where the hull was welded up by BP Marine near Bangkok. BP is a very expeienced yard for alloy boat fabrication and the workmanship was excellent - I don't plan to fair or paint it other than anti-fouling and deck non-skid.

My cruising ground is the trans-equatorial region of the W Pacific and Indian Oceans, where there are frequent calms. In an effort to improve passage making performance I expanded the fuel capacity of the bilge tanks, increased the power from the 39hp Yanmar saildrives to 50hp and have fitted self-pitching Autoprops. I also changed the headsail rig from overlapping jib and spinnaker/prodder to a blade jib and a roller furled flat cut screacher on a parallel headstay off a fixed sprit. The mast was also lengthened 2.5m to get a bit more sail area and higher aspect ratio to improve light air upwind performance..

I disagree with some of the postings on this forum that motorsailer rigs should be designed for off wind use. Let's say I'm headed due West on a 1500nm passage from Phuket to Chagos and am motoring at 7kts with one engine on a calm night. Since we cruise in the usual areas in the usual seasons, a nice 7kt NE breeze springs up at 120 degrees off the bow. This results in an apparent wind change (from 7kts dead ahead) to 60 degrees off the bow - not too good for your average MPS but no problem for the big flat cut screacher. Of course when the sails are actually deployed, the boat will speed up from 7kts, bringing the apparent wind even farther forward.

The boat was recently launched and was motored 1300nm from Bangkok around Singapore up to her home port of Phuket where she is again on the hardstand for interior fitout and rigging. The delivery took 6 1/2 days including 2 r&r layovers and a fuel stop. Motion under power was very pleasant with good pitch damping. I don't have a website but anyone seriously interested in this design can contact the builder at marineware at loxifo.co.th for more information and pictures, layout etc.just tell him I referred you off this forum please. I will update the forum when I can get good performance measurements.

Fair winds
Bob n6bk at yahoo.com

Note: forwarded message attached.

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Date: Sat, 29 Dec 2007 10:53:53 -0500
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From: Georgs Kolesnikovs <georgs at powercatamaranworld.com>
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Subject: [PCW] Motorsailer cat, was Anchors
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Bob Kupps wrote:

>On my 50' alloy (motorsailer) cat which has a cruising displacement 
>of about 10 tons

How about some information on your boat, Bob?

Designer? Builders? Specs? Cruising grounds? Cruising plans?

Are photos posted anywhere on the Web?

--Georgs
-- 
Georgs Kolesnikovs
   Power Catamaran World
   http://www.powercatamaranworld.com
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