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For prop shops, boat centres and marine engineers

Size it. Print it. Win the job.

Exact recommendations with full curves and cavitation checks, a PDF with your logo, the check on your own website, and quote requests from boat owners near you.

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PropbenchPRO
30 ft motorboat7.0 t · 55 hp · shaft4/6
EssentialsAdvanced
Boat30 ft · 7,050 kg⌄
Length overall30ft
Displacement7,050kg
Waterline length8.23m
Waterline beam3.11m
Estimated from length. Enter the real value for a sharper answer.
Engine55 hp · 2.50 : 1›
Prop on the boatNot entered›
Aperturemax Ø 19 in›
Design targetTop speed›
Advanced inputs: hull form, deadrise, rpm band, reserve, blade area, water →
Calibrate with a sea trialUncalibrated, the model was off by 11.7 % on top speed on 18 measured test boats. One logged run calibrates it to this boat.Log a sea trial
Updated in 0.28 s · engine v3 · 127 measured boats
Job 1042 · Mette K. ⌄

30 ft motorboat · 55 hp shaft drive

UncalibratedSea trialGenerate report
RecommendationCurvesSea trialsReport
Fixed 4-bladeFixed 3-blade2 types fit
Recommended19 × 14 inFixed 4-blade · bronze · EAR 0.55 · P/D 0.74 · RH
Full throttle3,010 rpm · in the band
2,000today ≈ 2,600band 2,900–3,0903,300
Race · 19 × 14 vs 18 × 15Expand ↗Speed through water6.2 kn+0.1 kn ahead
☆ Shortlist▶ Race in simCustom size
Top speed6.2 kn
Bollard pull ahead618 kg
Stop from 6 kn10.5 m
Efficiency η₀33 %

Where full throttle lands

Today (est.)19 × 14Engine
band0102030401.5k2k2.5k3k

Checks

3 of 5 pass · 1 to measure
Full throttle in the rated band3,010 rpmBand 2,900–3,090 incl. 3 % clean-hull reserve.
Back cavitation (Burrill)89 % of limitClose to the limit for this immersion. Fine for cruising.
Blade areaEAR 0.55 · needs 0.53Smallest area that keeps loading inside the limit.
Inside the tested B-series rangeP/D 0.74 · 4 blBlade count, area and pitch ratio all tested.
Tip clearance to hullnot measuredAim for 15 % of diameter: ≈ 72 mm for 19 in.
How sure: on 18 measured test boats the model was off by 11.7 % on top speed before calibration.
01 · Pro calculator

The exact prop, with alternatives per diameter.

For every diameter up to the aperture limit, the pitch that lands full throttle on rated rpm, ranked by speed with a cavitation penalty.

  • D × P, blades, blade area ratio
  • Current vs new side by side
  • Speed, fuel and range at every rpm
  • Cavitation, blade loading, shaft and gear checks
D × PP/DWOTknη₀Check
16 × 11.50.722,8907.30.51OK
17 × 10.50.622,9407.40.53OK
18 × 9.50.532,9607.40.55Tip clear.
02 · Branded report

A PDF your customer keeps, with your name on it.

The verdict, the recommendation, the curves and every input, on one page with your logo. Every report a customer passes on is marketing for your shop.

  • Your logo and contact details
  • Inputs and assumptions printed in full
  • “Prepared by [your shop] using Propbench”
[Your logo]REPORT 1042
Propeller recommendation024681,0001,5002,0002,5003,000KNOTSPrepared by [Your shop] using Propbench · every input on page 2
03 · Leads

Boat owners near you, with the boat already filled in.

Owners who run the free check can send their result to shops near their harbour. You get everything you need to quote.

  • Only with the owner's explicit consent
  • Only complete leads with a confirmed email
  • Included leads every month, extra leads per lead
New lead28 Oct 14:02 · consent given

34 ft sailboat · Volvo Penta D2-75

VerdictOverpropped · 2,550 rpm
Prop today17 × 12 RH · 3-blade
HarbourHaderslev · 6 km
Open in calculatorSend quote
04 · Embed

The calculator on your website, with your quote button.

One line of code puts the check on your own site. Owners who use it come straight to you.

  • Your colours and logo
  • Leads go only to you
  • Works on any website builder
yourshop.dk/propeller
Is your prop right?[Your logo]
Volvo Penta D2-75MS25L · 2.74:1Sailboat · 34 ft17 × 12 in
● OVERPROPPED · 16–17 × 10–11 INGet a quote from [Your shop]powered by propbench
Neutral maths

Payment never changes a recommendation.

R-01

Same maths for everyone

The recommended prop is identical whether or not anyone paid. Owners trust it, so they act on it.

R-02

Featured is labelled

Payment can decide who is listed first and who gets a lead. Paid placements always say Featured.

R-03

Owners choose

Boat data goes to a shop only after the owner ticks the box. Consent is stored with the lead.

The maths for your shop

It pays for itself with one job.

Work won / mo€1,200
Shop plan€99
Return12×
Your own numbers. Rudes Propeller pilot results: [to publish after 60 days]
Plans

From €99 a month.

Compare every feature
Shop€99

Boat centres, repair shops, dealers

Start trial
ProFor prop shops
€199+

Prop shops and marine engineers

Start trial
Enterprise€500+

Prop makers, distributors, importers

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Questions

From shops.

Do I need to install anything?

No. It runs in the browser, in the workshop or on the dock.

How do leads work?

Owners who run the free check near your area can send you their result, with consent. Each plan includes [N] leads a month; extra leads cost €10–40 each by job size.

Is my area exclusive?

Lead areas open region by region, starting in Denmark. [Exclusivity policy to decide.]

Who is responsible for the recommendation?

You are. Propbench is a decision aid; results are engineering estimates you check and stand behind. [See B2B terms.]

Try it on your next customer's boat.

13-day trial · real leads

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