Robalo Speed Question

[Searenity]

I have a 20FT 1074 Robalo, with a 1986 150hp/mercury OB.Bought the boat last season,spent most my summer working out some issues.It seems to run fairly well, but @ 5000 rpms ,which according to my Merc manual is tops for the engine I only see 32 MPH . I dont know the weight of the boat, and would appreciate any info on my hull.Robalo has been re bought so many times..the manufacturer cant help me and suggested I try a forum such as this. Basically if this speed sounds right, then so be it. But I would like to know. Also I have a new prop that was supposed to be the right one for my hull and engine.

 

[Searenity]

Re: Robalo Speed Question

thats 1974 for the year of the hull, sorry

 

[Dhadley]

Re: Robalo Speed Question

Are you sure you want to prop it to 5000 max? Sounds a little low to me. What brand, diameter and pitch prop do you have? If you get that info we can calculate slip and see where you are although it does seem slow. <br /><br />Also take the boat and trailer to a weigh station and weigh it. Then take the trailer back empty. Deduct the trailer, engine and load weight. The manufacturer can tell you the hull weight when produced. You should be close now. If not then you may have water trapped in the hull.<br /><br />Good luck!

 

[John from Madison CT]

Re: Robalo Speed Question

Older Robalos are notorious for holding many many pounds of absorbed water. (Water logged)<br /><br />My '78 18' Robalo had that problem. I didn't know a thing about boats back then. (~1987) and really had a lemon on my hands. The transom was shot too. The boat must have weighed at least 500 lbs more than it should have. I had a 115 Merc on it and it probably topped out in the low 30 mph range.<br /><br />You might want to find a truck scale to get it weighed.<br /><br />Good Luck,<br /><br />John

 

[krosemond]

Re: Robalo Speed Question

I have a 79 20' Robalo powered with the original Johnson 150. I pitched the prop at 15 and she turns about 5300 WOT. At 4000 RPMS, I make about 28mph cruise. I only tested top speed once on a glass like lake and it was only 35mph. I don't know what kind of waters you boat in, but I have never found that speed to be a concern in that hull. When I inherited the boat, it was pitched at 17, and was real slow out of the hole and didn't run right. Now she doesn't foul plugs and runs much better.<br />I also suspect a water logged hull and may take action to get the water out. I don't know if you have the in deck fish box, but I foamed mine in and sealed it. That thing was a nightmare, every drop of water that hit the deck landed in there.

 

[wilde1j]

Re: Robalo Speed Question

I can give you a somewhat similar reference. I have an old 19' Sea Ray w/ a 140HP Johnson. I routinely get 45 to 47 statute MPH with a reasonable load in the boat. Speed verified by LORAN and GPS in non-tidal water (lake). Your boat is way too slow for the motor size you're running.

 

[suzukidave]

Re: Robalo Speed Question

Congratulations, if it's in good shape that's a great boat Searenity even if you have to refoam it. I wouldn't trade it for a new one.<br /><br />There may well be water in there but overall that's just a big wide heavy deep v 20' boat for an older 150 that may be getting tired. I'm guessing that your 1974 is built just before the oil crisis made everyone start to cut back on glass. Do you have all the teak finishing above too? I don't own but do know a late 70's 21' robalo with a 225 merc (not sure if it's the same huill as yours). It'll make about 40 and took some prop fiddling to get a good hole shot. If you have to know, get a shop to look at it, but I wouldn't have expect much more than low to mid 30's from your rig. <br /><br />Wildeone, I don't think a 20' Robalo is comparable in weight or hull to a 19' Searay. It's a bigger beamier heavier boat with a deeper v.