Doel fins

Hello All

Quick question with regards to Doel fins. I just bought a 14 foot Dory for messing about in on the Shannon etc and close in sea work on calm days. She is an open type with no cuddy, dell-quay style hull and weighs a lot less overall than our Strikeliner (a lot less which I know from handling the trailer). I kept the strikeliner this is just a little addition.

She is fitted with a nice late 90s Suzuki 65 HP and the previous owner had Doel fins on it. I took them off. I dont think they are needed as I think there should be plenty of power there for that kind of outfit with a 65 on and I dont see a use for them.

We have them on our strikeliner but thats a near 17 footer with a cuddy and a 25 hp only and for that it might help plane at lower speeds. I have also been caught on the strikeliner with a following wave that seemed to catch the fins and raise the stern and I would like to avoid that in the Dory.

Was i right to take them off? I think I was

Thanks for any input

Adam

I cannot see the logic for having fins on an engine that has PTT. I take it the 90 has PTT? If you have the trim range on the engine to keep the bow down or up as required I cannot see the fins being a benefit. Have you had a run without the fins yet?
I once removed fins from an engine after fitting them as an experiment. Had to fill the holes as there was a ferocious jet of water underway.
Many of the Orkneys I have driven did not like a following sea. They tended to run off centre when running down the wave necessitating throttling back so they come back on line, not a nice feeling. I often think it could be from lack of power. The warrior loves a following sea, I wonder if it is a combination of V hull all the way to the stern and more power on tap than the average Orkney. It might be just an inherent quality of the Orkney-style hull rather than the fins. We had tabs on a Fastliner with 40 Yam non-PTT and the fins definitely helped performance.

Thanks Jim. I had a feeling you would be first reply!

No I have not run her at all yet. I might head down to the shannon next weekend with them on take a run and then take them off (takes two minutes) and go on the same run to see if I notice any difference in perfromance.

Yes it might just be the Orkney hull and the low power, the fins definitely seem to help the Orkney plane so I would have them on that but its only a 25 HP merc on the orkney.

Would you not swap the engines Adam?

Hi Pete

I had thought about that but the 65 seems to have come as a package with the boat and the throttle controls and ignition and all are matched to the engine. The rev counter and oil/ water flow warning lights are all on dials that are moulded into the steering console so I would have to take all that out too which would get a bit messy.

I dont think the strikeliner transoms are rated to 65 either

Right I am going to test the effect of the fins. Put them back on again last night. Will get out on the river on Sunday and run her over a mile and a half run I know on the river.

Starting off at a big buoy a mile run to a set of bouys, two tight circles around the two buoys and then another half mile to the finish. Will do up and back with the fins and then up and back without them following the same track on the GPS and will see if top speed, time to plane, stability on the plane, general handling and turning are affected.

Hi. Interesting topic. I bought my boat (Explorer Elite 50HP Honda) from Lencraft in Dungarvan a few years back (2005). I wanted them to fit fins but they wouldnt do it, they told me a boat they previously put them on had gone over while doing high speed tight turns on the Blackwater. They said the hull/engine combo had plenty of lift without them, as you suggested about yours Adam.

Hi Adam,

I would guess that a 65 will have no issues at all putting the Dory on plane, so fins would not be necessary....... but, they might give you quicker time to plane if you have no PTT. Without PTT you can trim the engine out a little to give a better ride at speed and keep her slightly bow high. In this config, it would normally take a little longer to get on plane at the fins would help here (but with a 65, who cares ) As you mentioned, you will not be out in a following Sea or lake and will use it for light inshore work, so I am thinking you might find that fins with the engine trimmed slightly out would be a nice set up.

Let us know how you get on with the test.

Kev