1987 10 meter express standard performance help

[mkcoxn]

I just wanted to ask people who own these boats what they are getting for speed and rpm's?

My boat has like new 330hp Marine Power 454 TBI motors with MG5000 2.0:1 tranni's and 18x22 props. The original crusaders with 1700 hours performed about the same last season before repower.

My boat is an absolute sled. I would like to see it plane out and get at least 25 kts max out of it.

I am making 18kts at 3000 rpm's. 20kts at 3500. Max rpm 3900. Am i overpropped?

I realize these boats do not have lifting strakes and struggle a bit.

Mike 781-706-3365

[RWS]

You should be reaching the WOT of 4400 RPM.

Overpropping is a possibility as is a dirty bottom, incorrect engine timing, failure of vacuum and or mechanical spark advance among other things.

What year and model is your 10 meter?

RWS

[wowzer52]

I agree with RWS, first thing I would do is clean the bottom and concider how much weight you are carrying. Without being loaded with fuel and stuff I get 4400rpm but after loading the boat with all our gear, fuel, food, stuff and junk I turn 4000rpm, With a dirty bottom I could only turn 3700 without the load.

[S.A.M.]

You're over propped. You need to drop to 19". The standard rule: @ 200 rpm per inch that would put you around 44-4500 rpm.

Are you running 3 or 4 blades?


Disclaimer;
Opinions vary and with free advice, you get what you pay for.

[mkcoxn]

The boat is an 87 regular cabin. The props are 3 blade 18 x 22's. I have a set of 18 x 20's, shoud i try them? The reason i went to 18 x 22's is because my previous tranni was 1.5:1 and the new ones are 2.04:1.

The boat is fully loaded. The bottom is clean but has many years of paint build up.

What are you getting for top speed at 4400? Does your boat appear to plane off at all? Meaning is there at a point once on plane that you can actually throttle down and maintain speed.

What are these boats rated for speed new with the crusaders?

Mike

[S.A.M.]

My midcabin is heavier and balanced differently than yours. So it's hard to make comparisons. My owners manual states that the gas engines came with 2.0:1 transmissions & 1.5:1 for diesels.

At 4500 rpm my gps reading is 29 mph half fueled. At 3000 rpm speed is 17 mph. At 2800 rpm speed is 14 mph. Unfortunately I have no idea what props are on the boat. The survey didn't list prop size and the boat runs smooth, but cruises slower than I'd like, with a full load.

RWS has published on here charts that show his performance with gas engines prior to his diesel.

I have the Trojan performance sheets, from my owners manual scanned.

PM me your email address and I'll send the pdf to you.

[rossjo]

http://www.BOATDIESEL.com Prop Calculator is THE best tool on the net (doesn't matter if its diesel or gas - you simply enter HP and RPM about your engines). Its $25/year to join, but FULL of good information beyond the calculators (prop, power and shaft size calculators).

http://boatdiesel.com/Members/MembersPrograms.cfm

PROPELLER SIZE


A program to determine the correct diameter and pitch of a propeller for any given vessel and engine.

Define your:
Vessel - displacement, semi-displacement or planing. Water line length in feet or metres and displacement in lbs, kgs, tons, tonnes or long tons
Engine - output in SAE hp, kW or metric hp, maximum rpm, manufacturers rating of either pleasure, light, medium or heavy duty.
Transmission - type and ratio.
Propeller - number of blades and if need be define a fixed diameter.

The program will then calculate: Maximum achievable speed, estimated fuel consumption, recommended propeller diameter and pitch, a propeller pitch based on a required fixed diameter, plus it will suggest alternative propeller sizes using different gear ratios to provide better propeller effeciency.
If you define a cruising rpm, the program will calculate the power produced, estimated fuel consumption and cruising speed you can expect with this same propeller.

[rossjo]

Castle Marine has a good calculator as well (download):
http://www.castlemarine.co.uk/pitch.htm

To calculate your speed/slip, use:
http://www.rbbi.com/folders/prop/propcalc.htm

[RWS]

With the gas engines I had 18x19 4 blades and a spare set of 3 blade 17x22

This is the 10 meter express cruiser, NOT the midcabin model which has different motor placement, gear reduction and propeller sizes.

I sent you the performance graphs seperately. The gas graph is for the 4 blade which provided better economy and lift than te 3 blade.

These boats will perform well with the 454's however many other factors can affect performance, including the condition of the engines, propeller choice, correctly sized and used trim tabs among other factors

RWS

RWS

[mkcoxn]

RWS do you have a loaded weight of your boat? My boat is not a mid cabin it is a standard express cruiser.

[RWS]

Published dry weight is 12,000 lbs.

We weighed mine fully loaded, full tanks, tools, spares, gear etc on a travelift and got a very rough, non scientific weight of about 16,000 plus.

This may be because my boat has numerous factory accessories, that add weight to the "base" boat.

2 referigerators, (ice maker) L bench seat, wetbar, generator, A/C rear bench seat, an additional layer of lead lined insulation under the entire cockpit floor, swim platform, genset fuel tank, microwave, etc etc.

Something is not right ifyou cannot get to 4400 RPM WOT

RWS

[sehord]

I get 18 knts @ 3000 RPM but max out at around 3400 RPM. I have not checked to see if the travel of the throttles is limited or if that is just my WOT. I do not know what size props I have, but now I will check and let you know. I seem to be in the same range of speed at 3000 RPM, so could it be over propped if the load speed at 3000 is that close?