Under contract to buy Sunseeker Portofino 46

hey guys, I’m under contract to buy my first larger boat and first boat that wouldn’t be trailered.

Ill include all the details below so you can take a look at the deal if you want and let me know what you think.

2005 Sunseeker Portofino 46
Length overall: 48ft 5in
Beam: 13ft 9in
Draft: 3ft 10in
Weight: 32400 lbs
Water capacity: 82.5 gallons
Fuel capacity: 288 gallons

Engines: Repowered in 2015 with Cummins QSB 5.9 engines 480hp - 600hrs
Transmission: V-drives and shafts with prop tunnels

Boat is in Houston area. Has stayed in that same area for many years and been sold a few times.
Boat lives in brackish water for good part of its life, and 100% brackish water since the repower.

Cruise: 2400RPM, 12GPM per engine, 20knots
WOT: 3150rpm, 26.6 knots top (dirty bottom) and burning 24.9 gallons/hr
Engine max Rpm = 3400
Test was done without bottom cleaning and boat needs a cleaning, so numbers arnt that good right now.

No smoke in exhaust

No maintenance records. So ill assume no maintenance was done.
Per Cummins owner manual, there isn’t really any service needed other than some basic checks and zincs until 500hrs. So 600hrs in brackish water shouldn’t be too much of a problem.

Local reputable diesel shop recommends aftercooler service/cleaning only every 1000hrs due to brackish water (we need it every year or 2 in south Florida), and bottom cleanings are only needed every 8 months in this area.

I have the prior survey from the sale 2 years ago. Most of the minor issues have been corrected since then.

Only 3 potentially major issues outstanding from prior survey:

1. two areas of moisture in core in foredeck (around/under layout pad I front deck).

2, Has crazing in gel coat in misc areas of the tower, and on sides above rub rail.
Has vertical stress cracks in gel coat amidships and aft above rub rail, on stbd side only. No delamination detected, no repair needed per surveyor.

NOTE: the other Portofino I saw had similar crazing issues. It could be a common problem on this boat?

3. Boat waterline is low in front. Water is 1in above the bottom paint line. possible soaked core up front adding weight?


PRICING
I pulled all the boat wizard comps on the Portofino and the equivalent Searay 460.
There are different ways of processing the comparables, but I tried to make adjustments for year of boat (2003 is worth about 7% less than a 2004, for example per NADA numbers) and I adjusted for the Covid boat price spike (boats prices spiked up 35% and then back down to 2019/2020 levels currently in 2024

I’m getting average adjusted comps = 180k
I could add 15k to 20k for engines probably, which would put me at 195 to 200k range.
I can get the boat for 197k, maybe a little less as well, depending on the results of the survey/seatrial in a week


QUESTIONS / CONCERNS:

1. I’m debating on whether to get engine survey or not. It’s got 600hrs on 2015 Cummins, and they lived in brackish water.

2. 5.9L 480hp Cummings Engines have a very high hp/ liter ratio. Normally a diesel making 480hp would be a 7.5 or 8+ liter. Regardless I should be looking at reduced engine life?
Seaboard Marine guys say the Cummins 5.9 is a great and reliable engine at all hp levels

3. Boat sitting low in water in front? Could that be due to water in the core from the forward deck leak? Im told that’s probably not the case by local surveyor. I'm going to do the haulout at a yard with a new travel lift that has scales on it, so I can get a weight on the boat and compare it to reference numbers (adjusting for fuel/water/oil, etc).

4. I know the crazing/cracking is expensive to repair, but im looking at some options on the forums/youtube for doing some decent repairs myself.
I can grind out the vertical side crack areas and fill with flexible epoxy, then paint over
I want to paint the entire boat anyway. Topside white and hull below rub rail a grey or maybe light blue/aqua color

5. Other boat options?
I was also looking at the Portofino 47, but they are priced way higher and not really worth it to me to pay that much extra for a very similar boat.

I also saw the princess v50, but no movable swim platform.

Thanks in advance for any feedback!


-Phil

ya the repower, especially with Cummins, makes it a much more appealing deal.
typically this boat has volvo TAMD 75 as OEM engines. ive also seen another one with Yanmar. one can only speculate why the engines were replaced so soon.

im not even sure its sitting low in the water. maybe the bottom paint just wasn't done right?

as far as painting. im gonna try to do it myself actually. as backup plan, i also got a quote for 20k for the hull, which is something i can afford if needed.

my main goal is to get a learner boat that i can make a few mistakes with and not break the bank.
i wont have this boat more than 3 years hopefully. learn how to do what needs to be done, make some less expensive mistakes, then move on to a larger boat.

yes, I was investigating the 5.9L Cummins as that was a concern.

As far as numbers accuracy, the fuel burn and rpm numbers I posted was from a phone video of the digital gauges on the helm while boat was operating on flat water at cruise and WOT.
So I would trust it

To investigate further, I pulled up the data for each engine

The original Volvo TAMD 75 makes 480 hp and 960lbs of torque at 2600 rpm. max torque at cruise speed (I'm guessing original cruise speed was 2000 - 2100 rpm) is about 1050 ft-lbs. max rpm is 2600.
The current Cummins QSB 5.9 makes 480 hp and 800lbs of torque at 3000 rpm. max torque is 960 ft-lbs at 2200 rpm. max RPM is 3400, but I see on the forums people running them at 3200 max to be safe.

I pulled up the hp/torque and prop curves to investigate. ill attach the data sheets.
from the data we can see that:

1. Volvo torque curve flattens out from from 1600 to 2400 rpm where it makes about 1000 to 1050 ft-lbs torque over that rpm range

2. Cummings torque curve isnt as flat. it makes 830 ft-lbs torque at 1800 rpms, toque peaks to 940 ft-lbs at 2200 rpms, and then makes 840 ft-lbs at 2800 rpms

I'm a little foggy on this, but as I understand it (correct me as needed), prop demand will be significantly less than peak engine output in the cruise rpm range. so even without any transmission or prop changes, the Cummins engine could still run the boat.
however the concern is to not overload the smaller engine in the cruise range, which could happen if the prop was too large.

We want the Cummins engine to reach peak rpm around 3200 and be fully loaded at that rpm. the measured fuel burn of about 25 g/h at 3200 rpm is about right from the engine data sheet.
We want the Cummins engine to be running at no more than 80% of peak output in the cruise range. the fuel burn rate of 12 GPH at cruise is 50% of peak burn rate of 25GPH, so that seems ok.


The fact that the Cummins is able to get to 3160 rpm and also be running at full load (based on observed fuel consumption at that rpm), would make it appear that someone did change or rework the prop (or possibly change transmission ratio?) to accommodate the different engine.

At cruise rpm, it looks like the Cummins is making about 10% less torque than the Volvo. this is significant, however I would think that could be adjusted for by reworking the prop or changing the prop.

Transmissions are the ZF280IV with 2.063 ratios, as was listed on the prior survey.
I will research these further.


Maybe someone who better understands prop matching than me can take a look at those data sheets and advise.
I also plan to call Seaboard marine and send them all the numbers and data and get their opinion on it before purchase.

ok, I pulled the original stats I posted from a website. I checked again, and for some reasons, I'm seeing some boats show 288 gallons fuel, and other 346 gallons. I checked the last survey and this boat shows 346 gallons fuel and 100 gallons water. so my mistake on that one.
with the cruise fuel economy I should still get about 250 to 300 mile range, which is more than enough for my use.

Weight is listed as 32400, so yes its light, although heavier than the equivalent SeaRay 460. Im planning to try to cruise on lower wind days only and slow down in heavier chop.

yes. live aboard is not my intended use. it will set at the dock behind the house. 90% local cruising and occasional trips to Bimini.

the purpose is to get experience and learn on a smaller boat. then later on upgrade to a 60ft.