Speed of 53c

[post42]

I need some input from any one that can help. I'm seriuosly interested in buying an early 70's 53c. I'm wondering what the cruise speed and top end are. Also the fuel consumption per hour. Engines are 1271 naturals 525 hp. The book says 17 knot cruise and 20 knot top, but I figured figures from actual owners are more accurate. Thanks guys, looking forward to hearing from you.
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[REBrueckner]

Sounds about right...see the 52c or 53c refit thread this same page...Pascoe covers some of this..

 

[NCBOAT]

Depends on whether they have full length spray rails. My 70 model 53c with naturals will cruise 19 maybe 20 with clean bottom and flat sea. But I have big full length spray rails.

 

[harnett]

I agree with ncboats numbers. I have the spray rails too but I didn't see any real change in speed by adding it. Maybe could call it a knot extra but that may just be because I didn't want to think I went to all that trouble for no reason. I am not convinced the spray rails are really worth it. Don't think they hurt anything though and they could be a small improvement.

 

[rtrafford]

do you notice her getting out of the hole any better with?

 

[REBrueckner]

I know some claim that full length sprail rails have a positive effect on speed, but simple logic argues against much of it.

Let's assume the spray rail provides 40 ft of 3 inch wide surface area relative to a half beam of maybe 7 ft...3" is 1/4 ft/7ft total so maybe bottom area goes up 1/28..maybe 3 or 4%. But you also get nearly that amount of increased drag, so any speed change would seem to be topped out at just a few percent maximum.

Trim tabs are also a small area but do have a small apparent effect. Of course they multiple their surface area effect via a downward thrust angle just aft of the props so a bit more effect would be expected. And they benefit from increased prop thrust as well. A trim tab 1ft x two ft would add 2 ft sq per side relative to the above spray rail of 1/4 x 40 or 1 square ft...twice the effect...

The above MAY be all wet, but I'd bet yacht designers would latch onto a "free" speed ride if one existed from spray rails. I can't imagine a typical full length spray rail matching tabs in lift, but I'm open to new information.

 

[harnett]

I can't honestly say that I noticed any difference at all. If there is one it is very small. In hindsight I think the spray rails were worthless effort. The thing that did make a big difference is weight. I ran the boat with all the interior gut, no tower of any kind, etc... Basicily the fiberglass, engines, and controls. She was three knots faster and sat almost two inches higher in the water. I have tried to be anal about weight while builder her back. It makes a difference. For example I've used cored panels building builheads and cabinets. I remade all the salon hatches with cored panels. Basically everthing I can think of to keep weight down. Anyone who says these things are too small of a percentage of the overall weight of the boat to make a difference doesn't know what they are talking about. I have seen the difference first hand.

 

[REBrueckner]

Huckins Fairform flyers have always used weight saving approaches to keep their speed up...from hanging curtains in place of doors to aluminum instead of stainless cleats, foam coring,etc,etc,etc. It works!!! Older Hatts with 2" thick solid glass bottoms, old style moderate HP DD diesels and Allison transmissions are just too heavy for best speeds. You get a package better aimed at longevity than than speed.

 

[dwaynec]

While it would be nice to have it all..... I will be content knowing that I have a very comfortable, seaworthy boat that has reliability and longevity built in, even if it is not very fast.

 

[rtrafford]

my refit has gone to the skin and back up. in doing so i've likely added 2000# below the interior decking in bulkheads and improved glass work throughout...significantly improved...

above the decks i'm going to use almost entirely coring and foam for construction thereby continuing to reduce weight ultimately relocating the center of gravity to a lower point as well. the flybridge will be nearly twice the size and weigh half as much...or thereabouts...

what we'll then have is an overall lighter boat, especially since the power has gone from the twin 1271N's to the 3406E800's and the power plant has shed a few pounds, too, going from the onan 15kw to the northern lights 20kw (a lot smaller than the old onan).

ultimately i think i'll be around 5-7k lighter than as original, and that should translate to a better speed. further in restructuring the hull we've stiffened it and minimized any porposing/flexing, something that should also affect speeds through greater efficiency.

now i just need to get her wet...

 

[rtrafford]

i've heard stories of older 53c's getting bigger HP that resulted in the boat laying over once the speed hit the upper 20's. we've been weighing this notion a lot recently, playing with ideas to hedge against that.

one concept was to build thin "wedges" along the aft 9 or 10 feet of chine to create some running surface that is more horizontal. i'm tempted to try this as the work and the removal wouldn't be a major issue for me, but i'd sure appreciate any input from the gallery.

likely i need to exchange with an engineer.