Defendant was charged with operating a boat under the influence of intoxicants. ORS 830.325 (former ORS 488.160).1 The state appeals from a pretrial order that suppressed both a non-Mirandized statement to a police officer and the results of a breath test. Reviewing for errors of law, we reverse and remand for further findings.
Defendant was lawfully stopped for operating his boat in excess of the posted speed limit at Hagg Lake in Washington County. With his overhead lights activated, Marine Patrol Officer Gregg pulled his boat alongside defendant’s boat and asked to see defendant’s certificate of registration. When defendant complied, Gregg noticed that he had trouble retrieving the document from his wallet and unfolding it. Gregg also smelled a strong odor of alcohol on defendant’s breath. Asked if he had been drinking, defendant replied that he had had “about a six-pack” to drink. Gregg retained defendant’s registration.
Suspecting that defendant was intoxicated, Gregg decided to conduct a field sobriety test. He testified that there were three people in defendant’s small speedboat, and he did not believe that it could hold another passenger, so he asked defendant to board the patrol boat. Defendant complied. Gregg then asked him to recite the alphabet, which defendant did very quickly, leaving out everything from K to Q. When requested to perform a thumb to finger count, defendant replied that he could not do that “even when he was sober.” Gregg then asked defendant if he would accompany him to the sheriffs boathouse to complete other sobriety tests that could not be performed on the patrol boat. Defendant agreed and allowed one of his passengers to take his boat to its trailer. Gregg transported defendant to the boathouse, which was located less than five minutes away. After they arrived, Gregg could not administer the tests because the boathouse was rocking; he asked defendant to perform the tests in the parking lot, but defendant refused to do so in public. Gregg then *532placed defendant under arrest,2 advised him of his Miranda rights and put him in the patrol car.
The passenger who was to have returned defendant’s boat arrived at the boathouse and reported that the third passenger, who was intoxicated, had thrown him out of the boat and was operating it on the lake. Gregg called for two more officers, one to stay with defendant and one to help Gregg retrieve defendant’s boat. After they secured the boat, Gregg took defendant to the Washington County Jail. The officer testified:
“I advised Mr. Greason that there is no consent form required on a crime like this, so I advised him that he could either take the [I]ntoxilyzer test voluntarily for me, or I could request a blood draw. He voluntarily took the [I]ntoxilyzer test.”
Defendant’s breath test indicated a blood alcohol content of .14. Approximately three hours had elapsed since the officer had first come into contact with defendant.
The state’s first assignment of error is directed at the trial court’s suppression of defendant’s statement that he could not complete one of the tests “even when he was sober.” Because that remark was made after boarding the officer’s patrol boat, the trial court surmised that defendant did not feel free to leave and that Miranda warnings were therefore required.
In determining when Miranda-like warnings are required under the Oregon Constitution,3 the proper inquiry is whether a person was in “custody” when questioned by the officer. State v. Walker, 104 Or App 410, 415, 801 P2d 877 (1990), rev den 311 Or 187 (1991). “Custody” encompasses both “full custody,” i.e., arrest, and circumstances that, although not rising to the level of full custody, create a “setting which judges would and officers should recognize to be ‘compelling.’ ” State v. Smith, 310 Or 1, 7, 791 P2d 836 (1990) *533(iquoting State v. Magee, 304 Or 261, 265, 744 P2d 250 (1987)). In situations involving either full custody or compelling circumstances, warnings are necessary.
Although defendant may have felt that he was not free to leave, that alone is not dispositive. For example, during a “stop,” which is “a temporary restraint of a person’s liberty by a peace officer lawfully present in any place,” ORS 131.605(5), a reasonable person would believe that he is “not free to leave.” State v. Horton, 86 Or App 199, 202, 738 P2d 609 (1987). Nonetheless, a valid stop may be followed by an officer’s reasonable inquiry, ORS 131.615(1), and generally that inquiry need not be preceded by warnings. Here, the officer did what was necessary under the circumstances to gather information to confirm or dispel his suspicion that defendant had operated the boat while intoxicated. Defendant complied with the officer’s request to board the patrol boat and their discussion occurred in public, alongside defendant’s boat and in the presence of his passengers. Like a motorist at a traffic stop, defendant could expect that he would have to answer some questions about his actions and that, unless his answers provided the officer with probable cause for arrest, he would shortly be on his way. His incriminating statement was spontaneous and unsolicited, and neither the setting nor the officer’s reasonable inquiry created an environment in which a reasonable person could feel that he was in custody and was being compelled to offer self-incriminating information. Therefore, Miranda-type warnings were not required, and the court erred in suppressing the statement.
The state’s second assignment of error is directed at the trial court’s suppression of the Intoxilyzer test results. It should be emphasized that defendant was not arrested for driving under the influence (DUII); he was arrested for boating under the influence. The Motorist Implied Consent Law4 *534applies to DUII, but does not apply to this offense.5 Therefore, defendant is not deemed to have impliedly consented to a breath test.
Curiously, the parties do not directly discuss whether the officer was authorized to require defendant to submit to the breath test. Instead, they assume that, if the officer was authorized to take a blood draw, then defendant’s consent to the breath test was a voluntary choice between the two alternatives. Although the precise basis for the trial court’s suppression is unclear, it appears to have involved a conclusion that defendant’s consent was not voluntary, because the officer lacked that authority.6
An officer who has probable cause to arrest for boating under the influence may either obtain a warrant for the withdrawal of a blood sample or, if exigent circumstances are present, require the withdrawal without a warrant. State v. *535Langevin, 304 Or 674, 748 P2d 139 (1988); State v. Milligan, 304 Or 659, 748 P2d 130 (1988).7 Langevin and Milligan compel the application of that rule to the expulsion of breath, which is a less intrusive procedure than withdrawing blood. For reasons that are not apparent, the trial court refused the state’s request for findings on whether the officer had probable cause to believe that defendant had committed a crime involving alcohol and whether exigent circumstances obviated the need for a warrant under the circumstances, because of the evanescent nature of alcohol. The court’s refusal to rule on that independent basis for denying defendant’s motion to suppress was error.
The court also erred in determining the voluntariness of defendant’s consent by looking only at whether the officer had authority to search. When a police officer indicates that he has the authority to apply for a search warrant, consent to a search induced by that threat may nonetheless be voluntary, because the officer is threatening “only to do what the law permit[s] him to do.” State v. Douglas, 260 Or 60, 488 P2d 1366 (1971), cert den 406 US 974 (1972). However, a threat to do that which is lawful does not, in and of itself, compel a finding that a subsequent consent was voluntary. In ruling on the voluntariness of a consent to search, courts look to the totality of the facts and circumstances. State v. Kennedy, 290 Or 493, 503, 624 P2d 99 (1981). A police officer’s threat to apply for a search warrant is but one factor. Others include, e.g., the time and place of the encounter, the number of officers present, the degree of hostility and whether consent was offered or requested. State v. Kennedy, supra, 290 Or at 505-06. The question is whether, under the totality of the facts and circumstances, consent to search was improperly compelled or induced. Circumstances, independent of the threat to do what is lawful, may render the consent involuntary.
We remand for findings on the voluntariness of the consent and, if consent was involuntary, on the presence of exigent circumstances.8
*536Reversed and remanded.