yanmar performance issue

[michaelmrc]

good day everyone my wife and i just went out for a sea trial on a 1980 catalina 27 with a brand new 1gm10 yanmar. this boat was advertised as being capable of cruising at 6knots but when we took it out it was only running 3.8 miles/hr at 3000 rpm, disappointed i asked the broker why it seemed so slow he told me that the bottom hadnt been out for a couple of years and that crud on the hull and prop were most likely the cause. myself being very new to sailboats am curious if this could in fact be the problem or are we looking at something else. any thoughts or suggestions ? thanks

[speciald@ocens.]

Sure can slow you down. Racers dry sail their boats for a reason. I didn't see in your note where the boat has been for the last two years but in Annapolis with brackish water - the bottom can get crudy in a few months. Realize that sailboats have much smaller motors than powerboats. Growth on the prop and bottom will have much more effect on speed through the water.

[AnchorageGuy]

If the bottom is fouled and the prop really fouled the boat will not perform well and I have seen instances where it would not even move.

[Talbot]

6 kts on a 27 ft boat with a 1GM - with a clean bum and a gale behind perhaps.

and it would have to be flat calm as welll!

5 kts more likely, and reducing considerably if wind against

[gonesail]

the catalina 27 is 7000 lbs ... so it seems a little underpowered with the 1GM 10. i had a 7000 lb. 28 footer with a 2GM and it would not do 6 knots under power.

[cantxsailor]

it would hardly move at all because the prop was so badly fouled. It looked like 3 balls of shells. Now I clean the prop every couple of months just to be sure. Even a light coating of small barnicles will slow my boat considerably. My YSM8R will push my PSC25(5000lb+ loaded) at about 5kts at full throttle with a spotless bottom and a clean prop. Usually I putt around at 3.5kts and don't strain the 30yo motor any more than required. I got good and stuck this weekend rescueing a couple of boneheads in a 12ft johnboat with a dead electric motor and only one lifejacket between them about a mile of shore. I had to really lay the coal to the old girl and she finally chugged her way free of the mud. I don't remember them saying much of a thankyou though......m

[Alan Wheeler]

I think you get the answer within the comments above. But certainly 6kts is being overly optimistic for a boat of that length. And any growth with that power is going to slow you dramatically.

[michaelmrc]

thanks everyone for all the info, had no idea that hull crud and growth would have such an affect on the performance.

[Ziggy]

Originally Posted by Talbot

5 kts more likely, and reducing considerably if wind against

I agree with Talbot, 5 knots in optimal conditions, less with fouled bottom or mismatched prop.

[Chief Engineer]

I have a question.

You say advertised at 6 knots but then say you were going 3.8 miles per hour.(3.2Knots)

How were you measuring your speed...over the ground or thru the water?

[Tropic Cat]

I have two 1GM10's (2 bladed props) in my boat and have to clean my props every 4 months. It takes about 30 minutes a prop unless I wait 6 months and then it's about an hour per prop.

If I don't clean them, I'm lucky to be able to move out of my slip at all, forget making any kind of speed.

[Boracay]

Boracay has a 22" prop so even with considerable fouling we still make good speed.
I had a 32' ferro a few years ago with a 7hp Yanmar and with the prop fouled it would not move at all.
With a waterline length of 36' we should be seeing 8.4kts but I'm lucky to get 7 most days.
With a waterline length of 21.75' you could be looking at 6.5 knots with all planets in perfect alignment. This does not happen very often.

[Celestialsailor]

I imagine you could possibly achieve 6+ knots....over a waterfalls...he he he

[michaelmrc]

chief we were using our lowrance x27 gps to tell us our speed.

[S/V Antares]

There are hundreds of Catalina 27's on the Chesapeake. Even with the 3 cyl universal they are a 5 kn boat. With any chop less. The dealer/broker is giving you bull.

Get online with one of the Catalina Owners groups and get some real opinions from other owners.