35 bruno stillman How to increase speed?

[captinchris]

1974 35ft bruno still
motor is cat 3208 355hp and twin disc 507 ratio is 1.54
Shaft size is 1 3/4 inch. Prop size is 19 - 21and 4 blade

what is best way to increase speed and power thing?
5blade and bigger size?
increase power?
any idea?
can you detail explain for me?

 

[F/V First Team]

You can only swing a 19" blade? Are you running a cage or what? Rails? (I am guessing that would be a no)

If your Cat is tired drop in a Sisu, slap a 2:1 on it and wind the pitch to your blade if you are limited on the diameter. Adding blades won't give you more speed or power, just a somewhat smoother arc through the water as the propeller turns.

When was the last time the bottom was done? And by done I mean removal of all paint down to the original gelcoat, smoothed and repainted. You might be surprised by the results.

 

[tunaorlater]

What kind of speed are you currently getting?

 

[fishinwishin]

My cousin says he will have to drop his out of a air plain to make his gp faster.

 

[Hooper]

Didnt the shaft size limit the hp that could be placed in those Brunos? Ive seen some repowered with Yamnars, 440

 

[MDI45]

Didnt the shaft size limit the hp that could be placed in those Brunos? Ive seen some repowered with Yamnars, 440

they dont have the room for a big enuff prop....thats one prob

 

[F/V First Team]

There is nothing wrong with 1.75" shaft
They will take some abuse

 

[Hooper]

they dont have the room for a big enuff prop....thats one prob

Maybe that was it, I knew there was some design issue which limited HP

 

[petrel]

How big of a prop can they turn? Someone on here is bound to know. 19 inches is tiny, but the reduction really limits it in that case. My 31' BHM swings a 26 square, but I'm sure the amount of horsepower going into those boats had increased considerably since Royal Lowell designed the 35' Bruno.

 

[Hooper]

I've always loved the 35 Bruno, most of the ones for sale have low hp engine by todays standards, 250 range. Like I said, most of the repowers seem to have been with Yanmars, 370 & 440

 

[Gundogs]

You are probably already a max hull speed for the hull design and horsepower. One way to increase speed and efficiancy without increasing horsepower would be to add substantial lifting strakes under the hull back aft. Look at the Hutt 46 hull in detail and see their strakes for ideas. We did it to a Downeast 42 and gained 2 knots. This resulted in a fuel reduction at current cruise.

 

[captainlarry84]

With a 355 CAT @ at 1:54 gear your propeller should be a 21 X 19 not a 19 X 21. Both wheels carry the same amount of load, however the 21 X 19 will give you better speed and performance by maybe 1.5 knots.

 

[tashmoo2]

You can get 16-17 knot cruise with a lobster finished hull and 20 pushing it with a 350 3208 CAT. prop diameter as mentioned before is the limiting factor. Lighten boat, remove all old bottom paint and make sure your hull is dry if cored. This is a great hull and very economical to run.

 

[tashmoo2]

I will ask guys I know what prop diameter you can swing. What style cabin do you have and has boat ever been weighed?

 

[captainlarry84]

Max diameter is 21" pitch is goverened by load. withy the 2:0 gera 19" max on pitch.

 

[tashmoo2]

My friend who owned 35 ft lobster style hull confirmed 21 x 19 as Capt Larry advised.

Hey Capt Larry, I am impressed. You gave me some good advice on my Harris. I just could not justify cost for hours I put on engine

 

[riskybusiness]

35bruno

i have a 35 five islands which is laid off the 35 bruno molds, with a 420hp 3126 i am doing 23kts with a comfortable 16-18 knot cruise swinging a 25x28 four blade, what they did wit the five islands is dropped the shaft lower and built a fiberglass drop skeg so you can swing a 25-26 inch wheel, if you have a wet log instead of a shaft tube it would be a relatively easy project to change out, but deffinetly an involved one

 

[riskybusiness]

I also have no sprayrails or lifting rails, i would imagine i could probably gain some more speed with the extra lift,

 

[captainlarry84]

i have a 35 five islands which is laid off the 35 bruno molds, with a 420hp 3126 i am doing 23kts with a comfortable 16-18 knot cruise swinging a 25x28 four blade, what they did wit the five islands is dropped the shaft lower and built a fiberglass drop skeg so you can swing a 25-26 inch wheel, if you have a wet log instead of a shaft tube it would be a relatively easy project to change out, but deffinetly an involved one

Correct on that a drop shoe rudder and lower the shaft on the Bruno’s is a big speed upgrade. However it is major surgery. Can you post a picture of your shaft and rudder change so others understand what all of this means.

 

[atlanticblue]

Riskybusiness, nice looking boat , I like that color!