32-3 Hull Speed?

[windblown]

I was pretty confident that our hull speed was 6 knots, or a bit more. We regularly get to 6+ under sail or when motoring, with an occasional 7 when surfing a following sea. But this past week, we decided to try out the old, heavy 155 Genoa that came with the boat, just for fun. Our SOG flew to 7+ knots and stayed there in a 10 knot breeze. So, what is the hull speed for a 32-3?

 

[southofvictor]

6.81 kts. 1.34 x sqrt(waterline length). to go faster than the through the water takes a lot of power. to go faster over ground just means the water has to be moving with you, which is way more common like in currents or on a wave face.

 

[HerbertFriedman]

I was out in SF harbor in my 87 E34 with 25+ kt and at slack tide the SOG was 7.9 kt which I believe is a bit above hull speed (LWL = 29.0 feet, so hull speed is 7.2 kt). Cleaned the bottom real well.

 

[Loren Beach]

Always ....... be sure that you or the person you are talking to is describing actual "hull speed" which is always your speed thru the water.
When you read off the SOG from your GPS, that's different thing altogether. Very useful for estimating your ETA at a destination, tho!

(I notice that a number of younger boaters locally do not know the difference. And since we boat on a river with variable current, and even that slows a lot or even reversed twice a day with tides, one cannot base their opinion of their boat's performance on SOG. At all.

For example, last weekend, we had almost no wind and motored up river to a club cruise at a state park. We carried the last of the flood tide with us part of way and our speed and SOG matched, and then we hit the true current and our SOG slowed a lot - down to 5.8 from the previous 7.1. Returning home, downstream, we were hitting 9.1 over ground (SOG) in some narrow stretches. Fun Stuff !!

 

[Prairie Schooner]

Always ....... be sure that you or the person you are talking to is describing actual "hull speed" which is always your speed thru the water.
When you read off the SOG from your GPS, that's different thing altogether. Very useful for estimating your ETA at a destination, tho!

(I notice that a number of younger boaters locally do not know the difference. And since we boat on a river with variable current, and even that slows a lot or even reversed twice a day with tides, one cannot base their opinion of their boat's performance on SOG. At all.

For example, last weekend, we had almost no wind and motored up river to a club cruise at a state park. We carried the last of the flood tide with us part of way and our speed and SOG matched, and then we hit the true current and our SOG slowed a lot - down to 5.8 from the previous 7.1. Returning home, downstream, we were hitting 9.1 over ground (SOG) in some narrow stretches. Fun Stuff !!

The current giveth, and the current taketh away?